ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 7 '21 



Cladocera we liave Bytliotrephes longimanus of Leydig and a species 

 of Dapknia. 



The pelagic fauna of fresh-water lakes consists of genera which, 

 like Piscicola or Argulus, are occasionally found there, and others 

 which do not voluntarily leave it ; the latter are divisible into such 

 as live on true pelagic animals or plants, like Acmeta, Vorticella, and 

 Epistylis, and others which are truly pelagic {Eupelagici Pavesi), such 

 as the genera referred to above and Bosmina and Leptodora. 



Lowest and Smallest Forms of Life as revealed by the modern 

 Microscope.* — The following are some of the principal jiassages of 

 the lectm-e delivered by the Eev. Dr. W. H. Dallinger, at the 

 Montreal meeting of the British Association. The ' Times ' says | 

 of it, " But, perhaps, the most popular and most generally 

 instructive feature in connection with biology at Montreal was the 

 address of Dr. Dallinger, in which he exhibited by word and jncture 

 the wonderful revelations of the lowest forms of life made by the 

 modern Microscope ; and in which he showed that however easy it 

 may seem to be to generate life in the proper conditions, no one has 

 ever yet succeeded in producing ' spontaneous generation.' And here 

 Dr. Dallinger is in accord with the most comjietent scientific 

 ojunion." 



Dr. Dallinger said : — " The labour, enthusiasm, and perseverance 

 of thirty years, stimulated by the insight of a rare and master mind, 

 and aided by lenses of steadily advancing perfection, has enabled the 

 student of life-forms not simply to become possessed of an incon- 

 ceivably broader, deeper, and truer knowledge of the great world 

 of visible life, of which he himself is a factor, but also to open 

 up and penetrate into a world of minute living things so ulti- 

 mately little that we cannot adequately conceive them, which are, 

 nevertheless perfect in their adaptations and wonderful in their 

 histories. These organisms, while they are the least, are also the 

 lowliest in nature, and are totally devoid of what is known as organic 

 structure, even when scrutinized with our most powerful and perfect 

 lenses. Now, these organisms lie on the very verge and margin of 

 the vast area of what we know as living. They possess the essential 

 properties of life, but in their most initial state. And their number- 

 less billions, springing every moment into existence wherever j)utre- 

 scence appeared, led to the question, How do they originate ? — do 

 they spring up de novo from the highest point on the area of not-life 

 which they touch ? Are they, in short, the direct product of some 

 yet uncorrelated force in nature, changing the dead, the unorganized, 

 the not-living into definite forms of life ? 



Now this is a profcnmd question, and that it is a diflScult one there 

 can be no doubt. But that it is a question for our laboratories is 

 certain. And after careful and prohjngcd experiment and research, 

 the legitimate question to be asked is : Do we find that in our 

 laboratories and in the obscured processes of nature now that the not- 

 living can be, without the intervention of living things, changed into 

 that which lives ? To that question the vast majority of practical 



* ' Times,' 2nd September, 1884. t Ibid., 4th September, 1884. 



