ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 51 



BOTANY. 



GENERAiL, 



Including- the Anatomy and Physiology of Seed Plants. 



Cytology, 

 Including- Cell-contents. 



Significance of the Chondriome. — A. Guillieemond {Rev. Gener. 

 Eotan., 1918, 30, 161-76, 13 pi.) publishes a further paper in support 

 of his theories as to the origin and nature of the chondriome. The 

 author claims that the elements of the chondriome, i.e. the mitochon- 

 <drias, are constituent elements of every plant or animal cell, and that 

 they are incapable of formation apart from existing mitochondrias. 

 The objection that the chondriome has no real existence, but is the 

 result of methods of fixation, is refuted by proof of its existence in 

 living animal-cells. A description is also given of epidermal cells of the 

 tulip and of the leaves and petals of L-is germanica, where structures 

 have been observed both in living and fixed material, precisely similar 

 to the chondriomes of animal-cells. It is also shown that the chon- 

 -driomes of both animal- and plant-cells behave in exactly the same 

 manner towards fixing and colouring reagents. Moreover, the elabo- 

 rating functions of animal chondriomes correspond to those of plant- 

 plastids, which the author regards as granular mitochondrias ; he points ' 

 -out in support of this theory that starch is not infrequently elaborated 

 before the amyloplasts are fully formed, and that the starch probably 

 arises from granular mitochondrias. Thus, it is claimed that the 

 elaborating function of the so-called plastids is not limited to the 

 formation of starch or chlorophyll, but that they participate in the 

 formation of the greater part of the secretory products of the cell. 

 Cytoplasm appears to be composed of a fundamental material of homo- 

 geneous appearance, enclosing in suspension the mitochondrias, which, 

 by a physico-chemical process still unknown, have the power of acting 

 as centres of elaboration of the greater part of the secretory products of 

 the cell. This confirms xiitmann's granular theory of the cytoplasm. 



The present work is supported by precise experimental data and 

 vital observations, which the author regards as entirely opposed to 

 Dangeard's vacuolar theory of chondriomes. S. Gr. 



Heterosis and Double Fertilization.— D. F. Jones {Bot. Gaz., 

 1918, 65, 324-33, 3 figs.) publishes a short note upon the results 

 of reciprocal crosses in maize. Collins and Kempton have previously 

 shown that one of the most remarkable effects of heterozygosis is 

 the increase in the amount of endosperm ; also that the weights of 

 the seeds themselves were greatly increased. The writer of the present 



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