PROCEEDINGS OF THE SOCIETY. 195 



Microscopic Pond-Life which had been arranged by Fellows of the 

 Society and Members of the Quekett Microscopical Club. 



Mr, Scourfield said that before dealing with the Pond-Life Exhibi- 

 tion he would like to call attention to the book on Fresh-water Biology, 

 by "Ward and Whipple, which had been presented to the Society. It 

 was a book that should prove extremely useful to all students of Pond- 

 Life, for although it would not replace the monographs and papers with 

 which the specialist in each group had to work, it was certainly the most 

 comprehensive single work on Fresh-water Biology that had yet 

 appeared in English. Dealing as it did with the American fresh-water 

 fauna and flora, some of the species, and even whole groups of species, 

 were peculiar to that continent, but after all the great majority of the 

 forms were the same as in this country, and the book could be highly 

 recommended to those who wished to have a general review of all types 

 of pond life organisms in one volume. 



In regard to the Pond-Life Exhibition that evening Mr. Scourfield 

 said he thought it was self-evident that one of the good features about 

 such exhibitions was that they encouraged the study of the living 

 organisms. This was all to the good, for there was a big field for work 

 in this direction in spite of what had already been done. We were 

 undoubtedly very ignorant about the natural activities of many, perhaps 

 most, aquatic creatures, both fresh-water and marine, and naturally the 

 only way of acquiring such knowledge was by studying the organisms 

 while they were alive. Without entering into all the ramifications, 

 bionomical, physiological, etc., of the study of living organisms, he would 

 nevertheless like to refer to a few cases in which correlation of structure 

 or other modification to particular modes of life or conditions of existence 

 could only be understood by a study of the Uving organisms. 



Taking first the adaptations for life among weeds and algse, many 

 modifications were to be found for the purpose of attachment, some of 

 which were not at all evident at first sight. For instance, there was 

 tSimocephalus, one of the Daphnids, which was enabled to cling to 

 weeds, and even glass, by means of an excessively minute hook at the 

 tip of one seta only on each of the large antennae. The hook was so 

 minute and inconspicuous that no one could have guessed its use if the 

 habits of the living animal had not been studied. And yet the posses- 

 sion of these tiny hooks made the most profound difference in the life 

 of the animal, for instead of having to " hop " incessantly, as was the 

 case with the nearly related Daphnia, it could suspend itself as long as 

 it liked without effort. Equally remarkable organs of attachment were 

 possessed by Sida and Graptoleberis, the former having a special organ 

 at the back of the neck, and the latter a flattened ventral margin 

 fringed with densely plumose sette. In both cases it would have been 

 impossible to have foretold tlie use of such modifications except by 

 Avatching the living animals. 



In connexion with adaptations for planktonic conditions of existence 

 the case of Diaptomus and its allies might be mentioned. In these 

 Copepods the second antennte and the maxillge were used as accessory 

 organs of locomotion, which by means of very rapid vibrations enabled 

 the animals to glide through the water without the necessity of using 



