SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



Z O Li O G Y AND BOTAN Y 



(PRINCIPALLY INVERTEBRATA AND CRYPTOGAMIA), 



MICEOSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



a. Embryology, f 



Cluster Formation of Spermatozoa.} — Jacques Loeb finds that 

 when tilt- spermatozoa of a sea-urchin are placed in sea water which 

 has been standing above eggs of the same species they form temporary 

 clusters. The cluster formation resembles the phenomena of surface 

 tension in varying respects, e.g. the clusters tend to Vie spherical, and 

 two clusters fuse into a larger one. When sperm is put into ordinary 

 sea water or into the supernatant water of foreign eggs these apparent 

 surface-tension phenomena are not observed. In real sperm agglutina- 

 tion neither cluster formations nor the above-mentioned surface-tension 

 phenomena are noticeable. 



It was found that the cluster formation is a direct function of the 

 motility of the spermatozoa. As soon as the spermatozoa are immobilized 

 by NaCN, or by a high temperature, or by KC1, the cluster formation 

 ceases. When the motility returns the cluster formation occurs again. 

 The real agglutination of sperm occurs just as well when the sperm is 

 immobilized as when it is motile. 



The clusters last only a few minutes, like Lillie's sperm "agglutina- 

 tions." They last longer in a neutral than in an alkaline solution. 

 Loeb suggests that the phenomenon is essentially or partly due to a 

 negative" chemotropism of the spermatozoa to the egg water. B 

 which have been treated with acid sea water lose permanently their 

 power of producing a substance which causes the cluster formation of 



* The Society are not intended to be denoted by the editorial " we," and they 

 do not hold themselves responsible for the views of the authors of the papers 

 noted, nor for any claim to "novelty or otherwise made by them. The object of 

 this part of the journal is to present a summary of the papers as actually pub- 

 lished, and to describe and illustrate Instruments, Apparatus, etc., which are 

 either new or have not been previously described in this country. 



t This section includes not only papers relating to Embryology properly so- 

 called, but also those dealing with Evolution, Development, Reproduction, and 

 allied subjects. 



X Journ. Exper. Z-ool.. xvii (1914) pp. 123-40. 



Aug. 18th, 1915 - B 



