304 SUMMARY OF CURRENT RESEARCHES RELATING TO 



determine that the relation of carbon dioxide given off to that of oxygen 

 absorbed depends largely not only on the quality, but also on the quan- 

 tity, of the nutrient medium. 



Sensitiveness of Ferments and Protoplasm to Physical and Chemi- 

 cal Agencies.* — Th. Bokorny discusses the sensitiveness of unorganised 

 ferments towards light and temperature, salts of alkalis and metals, 

 acids, alkalis, and some organic compounds. The enzymes noticed are 

 diastase, invertase, maltase, pepsin, trypsin, papain, rennet, emulsin, 

 myrosin, zymase. Considerable resemblance is shown by protoplasm 

 to the influence of reagents which have a deleterious action on enzymes, 

 though the latter frequently bear up against a greater percentage 

 quantity. 



B. CRYPTOGAMIA. 



Cryptogamia Vascularia. 



Spermatozoids of Ferns.j -r- Dr. A. H. E. Buller has studied the 

 following points in the physiology of the spermatozoids of ferns, the 

 species experimented on being exclusively Gymnogramme Martensii : — 

 Chemotaxis ; the withdrawal of water from the spermatozoids ; the length 

 of the swarming period ; and the history of the starch in the vesicle. 



The chief chemotactic ageuts on the spermatozoids of ferns are malic 

 acid and its salts, chiefly one of the latter ; but many other organic and 

 inorganic salts present in the cell-sap may exercise a positive chemo- 

 tactic stimulus upon them. Sugars, alcohols, asparagin, and urea have 

 no attractive influence. The attracting neutral salts do not give an 

 unmistakable tonotactic repulsion at high concentrations ; if such a 

 repulsion occurs, it does not prevent the spermatozoids from finally 

 entering concentrated solutions where they are brought to rest by loss 

 of water. The repulsion exercised by malic and maleic acids is chemo- 

 tactic. The withdrawal of a certain quantity of water from the sperma- 

 tozoids brings them to rest ; recovery takes place on resorption of the 

 water. The protoplasm of the spermatozoids is penetrated very slowly 

 or not at all by sugar and neutral salts, rapidly by glycerin, and very 

 rapidly by alcohol. In the case of Gymnogramme Martensii the swarm- 

 ing period lasts for about two hours ; in other cases it is shorter. The 

 starch in the vesicle of the spermatozoid disappears during the swarming 

 period. 



Schizsea pusilla.J — Mrs. Elizabeth G. Britton and Alexandrina 

 Taylor give an account of the life-history of this little known fern. 

 The following are the more important points. The spores are small, 

 nearly reniform, and have a cuticularised exospore which is alveolate. 

 It remains attached for some time after the formation of the antherids. 



The gametophyte is a filamentous protoneme, irregularly branched, 

 bearing both antherids and archegones on the same filaments. The 

 antherids occur singly or in groups on special branches which do not 

 bear archegones ; they are produced in great numbers, though but few 



* Chem. Ztg., December 1900. See Bot. Centralbl., lxxxv. (1901) pp. 293-5. 



t Ann. of Bot., xiv. (1900) pp. 543-S2. 



j Bull. Torrey Bot. Club, xxviii. (1901) pp. 1-19 (6 pis.). 



