DEPARTMENT OE MARINE BIOLOGY. 133 



Treated with H2SO4 in the proportion, i drop of N/io acid to 5 of culture 

 fluid, A is killed in about 5 seconds, D somewhere between 5 and 30, the 

 exact time not being noted. C in about 30 seconds, and B only after an hour 

 and a quarter. B is therefore 900 times as resistant as A and 150 times as 

 resistant as either C or D. 



The effect of KOH of the same strength is quite different. A is killed in 



2 minutes, D in something less than three-quarters of an hour, B in about I 

 hour, and C in 3 to 4 hours, C being about 100 times as resistant as A and 



3 to 4 times as resistant as B. 



The general result of these experiments is to show a surprising difference 

 in the resisting powers of the parasites of Diadema to various changed envi- 

 ronments. In some cases the most resistant form may live several hundred 

 times as long as the least resistant. Furthermore, a form which is strongly 

 resistant to one condition may be only feebly so to another, and vice versa. 

 For example, B is 8 to 10 times as resistant to HjS as C, but 1,500 times less 

 resistant to the products of proteid decomposition. C is more resistant to 

 CO2 than A or D, but less resistant to HgS. A, C, and D are 24 to 450 times 

 more resistant to KOH than to H2SO4, while B is somewhat less resistant, 

 etc. These and other similar facts that might be adduced show that each of 

 the forms in question has certain physiological traits that are almost as char- 

 acteristic and well-marked as its morphological ones. Furthermore, so far 

 as the evidence obtained from these experiments goes, there is no reason to 

 suppose that the similar habit of life in the parasites of Diadema has suc- 

 ceeded in bringing about physiological similarity, except in such adaptive 

 characters as are necessary for existence within the same host. 



Report upon the Dimorphic Spermatozoa of Marine Prosohranchs, by 

 B. B. Reinke, Princeton University. 



The most accurate and complete description of the development of the 

 dimorphic spermatozoa found among certain marine and fresh-water proso- 

 hranchs has been given by Meves in the case of Paludina vivipara. He has 

 named those spermatozoa which function in the ordinary way "eupyrene" 

 and the others "oligopyrene," and has described the growth period of the 

 spermatocyte as showing the earliest differentiation, in their development, 

 between the two kinds of male sex-cells, while the spermatogonia or their 

 ancestors are common to both. 



This differentiation, however, can be traced further back. I have observed 

 in the testis of both Paludina and Urosalpinx cinerea, at an early stage of 

 their seasonal development, that the "Basalkerne" of Platner are in some 

 cases swollen into tremendous proportions, while in others the already swol- 

 len nuclei are in various stages of fragmentation. These nuclear fragments 

 round out into ordinary nuclei and begin to push out from the syncytium in 

 which they lie into the interior of the lobule of the testis, taking with them 

 a covering of cytoplasm, which, however, retains a connection with the syn- 

 cytium. The cells thus formed become pear-shaped and grow rapidly, so 

 that they can readily be distinguished from the eupyrene spermatocytes by 

 their greater size. In Paludina the development of the oligopyrene sperma- 

 tozoa from these cells occurs as described by Meves. 



In the summer of 1910 I obtained a few specimens of Littorina nehulosa 

 from Jamaica ; and, upon sectioning them, I found that although only eupy- 



