156 A. H. REGINALD BULLER. 



No definite cliemotactic reaction — neither attraction nor 

 repulsion — was observed in any case. Into tubes containing 

 tlie weaker solutions the spermatozoa went in and out with 

 n])parent indifference. On coming- into contact with highly- 

 concentrated neutral substances (potassium nitrate 10 per 

 cent., sodium chloride 5-8 per cent., grape sugar 18 per cent.) 

 the spermatozoa came to rest from loss of water. They are 

 evidently not able to avoid solutions by a negative tonotactic 

 reaction. On coming into contact with strong acid solutions 

 (oxalic acid 0'9 per cent., 009 per cent., nitric acid 1 per 

 cent., 0"1 per cent.) the spermatozoa were killed, and thus 

 formed slight collections. They were tlius not able to avoid 

 acids by means of a negative cliemotactic reaction. 



Having obtained, so far as chemotaxis is concerned, only 

 negative results by means of the capillary tube method, 

 another method was employed, which Massart ^ found effective 

 in determining the tonotactic sensibility of a number of 

 marine micro-organisms. 



Two lai'ge and equal drops wore made in a moist cliamber; 

 one was of sea-water containing spermatozoa, the other 

 distilled water. The drops were then joined by a narrow 

 bridge, so that diffusion between them could take place. 

 The experiment was watched between one and two hours. 

 Some spermatozoa gradually entered the fresh water. No 

 collection, however, took place in either drop. There were 

 thus no signs of attraction or repulsion. The spermatozoa 

 that entered the too diluted water were killed. 



In another experiment a small drop of sea-water was dried 

 upon a glass slide. A large oval droj) of sea-water contain- 

 ing motile spermatozoa was then placed near and spread so 

 that one end just covered the crystals from the dried drop. 

 The crystals began to dissolve rapidly, locally concentrating 

 the sea-water. As diffusion from the concentrated end of 

 the drop look place the spermatozoa in the neighbourhood 



' j\lass;irt, " Reclierclics sur les Orj^aiiismes Infcrieurs. IT. Tia Scnsibilite 

 a la ("oiiccnl ration olicz Ics Elrcs Uiiici-lluiaiics Mariiis," ' Bull, del 'Acad, 

 loy. lie Bclgiciuc,' 3nie bcr., tonic xxii, Ko. S, IS'Jl, p. 14S. 



