ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 75 



its flowers ; the plants used were spinach, hemp, and Mercurialis annua. 

 These have been treated with manures in which one of the following 

 elements predominated : nitrogen, potash, phosphoric acid, chalk, and 

 sodium chloride. In the hemp and Mercurialis no obvious influence 

 on the number of male or female plants could be observed ; but in the 

 case of spinach, especially the Dutch variety, the effect was a marked 

 one. Two distinct effects were noticeable. In the first place, there was 

 a direct effect on the sex of the plants observed ; in the second, the 

 nutritive elements reacted on the sex of the embryos produced by these 

 same plants. As regards direct action, an excess of nitrogenous manure 

 or of chalk gives more male plants, while potash and phosphoric acid 

 cause an increase in the number of the females. As regards the second 

 effect, the seeds of plants cultivated with an excess of nitrogen produced 

 fewer male plants, more female, and among the monoecious individuals 

 a larger number of female flowers. On the contrary, an excess of 

 potash, phosphoric acid, or chalk, predisposes the seeds to yield more 

 male plants among the dioecious individuals, and more male flowers 

 among the monoecious individuals. In two years the descendants of 

 the monoecious plants of the Dutch spinach were tabulated. Seeds 

 were taken from a plant, of which the main axis bore female flowers, 

 while on the branches the male flowers were more numerous. In the 

 first year (1899), 100 large seeds gave 72 plants comprising 46 males, 

 13 monoecious and 13 females; 100 small seeds of the same origin 

 gave 21 plants, of which 17 were males, 2 monoecious and 2 females. 

 In the second year (1900), 200 seeds of medium size gave 98 male 

 plants, 23 female and 29 monoecious ; and among the latter there was 

 only one in which female flowers preponderated. These results, asso- 

 ciated with the general preponderance of male over female flowers in 

 Dutch spinach, suggest that the monoecious plants are males, in which 

 a certain number of flowers have become female. 



Chemical Changes. 



Experiments on Yeast Extract.* — J. Meisenheimer finds that even 

 when yeast extract is considerably diluted (1 in 25) it still has strong 

 fermentative properties. With water alone as the diluent, the activity 

 is largely destroyed ; dilution with 10 p.c. glycerol solution, or with 

 10 p.c. egg-albumin solution, does not destroy the activity. Impure 

 zymase may be precipitated from the extract by the addition of large 

 amounts of acetone (10 to 1), and the product is similar in all respects 

 to that obtained by the use of ether and alcohol. Trommsdorff's state- 

 ment that the proteids undergo a change during extraction from the 

 yeast is not correct, as the dry residue gives the same reaction with 

 Gram's reagent as the yeast itself. Small amounts of acetic and lactic 

 acids are formed during the fermentation of sugar solutions with the 

 extract freed from yeast cells. 



Co-efficient of Respiration of Yeasts.f — E. Wosnessensky and 

 E. Elisseef give the tabulated results of experiments with different 



* Zeit. Physiol. Chem., xxxvii. (1903) pp. 518-26. See also Journ. Chem. Soc., 

 lxxxiv. (1903) i. p. 591. t Centralbl. Bakt., x. (1903) pp. 629-36 (1 tig). 



