ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 333 



numerous families and of widely different habitat, with the object of 

 proving whether, as suggested by Bertrand and others, they contain a 

 diastase. The authors conclude that dry seeds usually contain per- 

 oxy diastase (i.e. diastase and peroxide of hydrogen). It appears to be 

 located in the embryo, but does not maintain its existence indefinitely. 

 The duration of its existence will be made the subject of a future 

 research ; at present it appears to have some relation to the age of the 

 seed. It may also be supposed that there is some connection between 

 the peroxydiastase of the resting seeds and the true oxydases of active, 

 living plants. 



Structure and Development. 

 Reproductive. 



Origin and Fruit-development of Acorus Calamus.* — M. Mucke 

 has investigated the fruit-formation of Acorus Calamus, and is of the 

 opinion that the cause of the arrest of fruit-development must be sought 

 in the unfavourable climatic conditions of its new habitat, since it was 

 originally a native of the warm regions of eastern Asia, and was not 

 brought to Europe until about the middle of the sixteenth century, 

 when it was imported into Germany. Indian and European plants show 

 a certain difference in their habit and behaviour under different con- 

 ditions of culture. Acorus has a stratified perisperm which incloses 

 characteristic albuminous cell-contents, and is absorbed by the growing 

 embryo-sac. The pollen and ovules in A. Calamus undergo an arrest 

 of development which prevents seed-formation, while, on the contrary, 

 there is normal development in A . gramineus, which therefore produces 

 seeds capable of germinating. 



Pollen-development of Sarracenia.f ■ — M. L. Nichols has made 

 cytological studies of the pollen of Sarracenia flava, S. purpurea, 

 S. variolaris, S. rubra, and 3. psittacina, and also of hybrids of S. flava 

 x S. variolaris, and S. flava x S. purpurea. The writer agrees with 

 those authors who believe that there is a connection between the 

 nucleolus and the formation of chromatin, and quotes the relations of 

 the nucleolus and the chromatin in the prophases of the first matura- 

 tion division in support of her opinion. The variation in the staining 

 properties of the nucleolus at this period indicates some sort of chemical 

 change, and the material thus elaborated escapes into the nuclear sac, is 

 absorbed by the linin, and distributed along its threads. The nucleolus 

 does not appear to have the same definiteness of function as the chromo- 

 somes and centrosomes, and it is probable that it represents a different 

 physiological activity at different times and in different cells. The 

 present investigation has not made it possible to determine whether 

 there is a conjugation of chromosomes during the synapsis stage, neither 

 does the behaviour of the nucleolus entirely favour the individuality of 

 the chromosomes. 



• Bot. Zeitschr., lxvi. (1908) pp. 1-23 (1 pi.). 

 + Bot. Gazette, xlv. (1908) pp. 31-7 (1 pi.). 



