i897. NOTES AND COMMENTS. § 



to American workers but to biologists everywhere. The two reports 

 on Rotatoria by Mr. H. S. Jennings, that on Cyclopidae and Calanidae 

 by Professor C. D. Marsh, that on the Turbellaria by Dr. W. M. 

 Woodworth, and that on the Parasitic Worms by Professor Ward, 

 are especially noteworthy. But even more important than this work 

 on the different groups of animals and plants was the application of the 

 methods, recently developed by Hensen and Apstein, to the estimation 

 of the amount and distribution of the " plankton," i.e., of the minute 

 plants and animals found floating free in the water, which form, in 

 the last resort, almost the only source of the food-supply of fishes in 

 large and deep lakes, and play a not unimportant part in this respect 

 in smaller and shallower ones. The results obtained in this way are 

 of the greatest scientific interest, confirming, as they do, many of the 

 observations of Apstein, Zacharias, and others on the plankton of 

 European lakes ; nor can they fail to be of value in the practical work 

 of fish-culture. The Commission is certainly deserving of all praise 

 for undertaking this biological examination of the Great Lakes, and 

 we can only regret that the work cannot be carried on continuously, 

 instead of being limited to a few weeks in the summer. 



In connection with this subject, we may mention that we have 

 received a copy of " The Illini," the weekly journal of the University 

 of Illinois, giving an account of its biological experiment station, the 

 first to be started in the United States with an adequate equipment. 

 This station also differs from others in having for its basis of work the 

 system of life in a river. The article, which is written by Mr. C. A. 

 Kofoid, has some excellent illustrations, and we hope it will soon be 

 possible to give an equally interesting account of a British fresh-water 

 biological station. 



A Starfish " Struggle-for-Lifer." 



There lives in the Mediterranean, as well as in the adjacent 

 parts of the Atlantic, an ally of our common crossfish, known as 

 Asterias richardi. Professor Perrier, who first described the species, 

 noticed the pecuHar fact that the young were provided with six arms, 

 whereas the adults had no more than five. Since he also observed 

 cases in which three of the arms were much smaller than the rest, he 

 assumed that the species was accustomed to reproduce by fission 

 during its youth, but that in its old age it sobered down to the more 

 usual method of reproduction. It appears, however, from the obser- 

 vations of Dr. E. von Marenzeller, that the arms are thrown off, after 

 the not uncommon custom of echinoderms, while the disc that 

 remains behind buds out fresh arms {See Natural Science, vol. v., 

 p. 4, July, 1894.). The curious point remains to be explained, that 

 the young is more given to this operation than is the adult, as well as 

 the fact that in old age there seems to be a cessation of regeneration, 

 so that some individuals have only two or three arms. 



The reason, according to Dr. von Marenzeller, is as follows : — 



