RECENT PROGRESS IN BIOLOGY.
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great interest Mr. Caldwell's account of what goes on inside these eggs while the young one is growing there; that is to say, an account of the differences and resemblances between the structures which gradually arise in these mammals' eggs and those which are familiar to us as occurring in the case of the common fowl.
With regard to the strange fish, Ceratodus, Mr. Caldwell has been no less successful, after much disappointment and persevering search. He has lately sent home a series of photographs showing groups of the black men and women whom he employed to catch the fish, standing by the river-side and holding each one in his arms a newly captured specimen, while some twenty or thirty more of the fish are heaped on the ground. Four years ago, zoölogists were glad to buy spirit-preserved specimens of this fish in London for twenty pounds apiece. Mr. Caldwell has as yet sent home so few reports of his doings in Australia, that every one will be interested in the following letter written from New South Wales in February last:
I shall give you a short account of my doings without apologizing for talking about myself, because you asked for this. When I wrote you last I was just beginning my camp-life on the Burnett River, and was very much concerned about my failure in the search for Ceratodus-eggs. I had invested in an American trap and horses and all the necessaries for camping out. I remained under canvas from the end of July to the end of November. Roget, my Belgian servant, was the only white man with me, but the blacks kept continually coming and adding to the number of my retainers. I had in the end about fifty of all ages—men, women, and children. I have sent you some photographs which I took during these months. I carried my camera everywhere, and the pictures will give you a fine idea of bush scenery and the roads (?) we had to traverse. I became very expert with my four-in-hand. It is a very different thing from driving a team along good roads; but I was fortunate in never having a serious smash. The blacks were more than useful: I could have done little or nothing without them. They found over five hundred Echidna in four weeks, while the "gins" searched the weeds of the river for Ceratodus-eggs. Let me tell you how I found Ceratodus-spawn. From the 24th of April (1884), when I found males ready to spawn, I had a pair, male and female, under constant observation in a small water-hole. Up to the beginning of September, though I was constantly dredging and turning up the river, I got no clew to the spawning ground. I determined to give up the search for the year, as further stay on the Burnett interfered with my plans for collecting the eggs of the duck-mole. All August I had been getting the eggs of the duck-mole, containing very early stages of the young; but with September the eggs had all been laid, and my plan was to shift my camp south to the colder district of New England, where, as I found in 1883, the duck-mole is a month or six weeks later in breeding. One evening early in September I was shooting duck-moles as usual, when I came to a place on the bank of the river where I could see several Ceratodus swimming about backward and forward in shallow water. It was too dark to look for anything that night, so I marked the place and described to the blacks what I expected. They were down at the river by daylight, and shortly afterward returned with Ceratodus-eggs. The egg is like that of a newt, and is laid in the water-weed, every egg separately. This changed my plans. I hoped
