ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 479 



2-3 times its original size, and during this expansion the membrane is 

 gradually withdrawn from the chromatin, with the result that a large 

 clear area of nuclear sap is left, at the side of which is the mass of 

 chromatin. This gave the appearance of a contraction of the chromatin, 

 but actual measurements failed to show any diminution in area. 

 Definite changes take place in the nature of the chromatin during the 

 formation of the spireme. It appears that the number of threads 

 forming the reticulum corresponds to the diploid number of chromo- 

 somes. The chromatin threads appear to be double even in the 

 reticulum stage ; they gradually shorten and thicken until they form 

 definite chromosomes, but there is no evidence of their blending or 

 fusion. Actual reduction occurs much later than the synapsis stage. 

 The author regards synapsis as a growth-period of the nucleus during 

 which the increasing karyolymph produces great osmotic pressure from 

 within, resulting in an enlargement of the nuclear cavity towards the 

 point of least resistance ; the chromatin mass is left behind, and its 

 position is a perfectly natural one. 



Mycoplasm Hypothesis and Metachromatic Corpuscles.* — J. 

 Beauverie contributes a brief note dealing with Eriksson's " mycoplasm 

 theory " in reference to the infection of cereals by blight. The author 

 has discovered numerous metachromatic corpuscles in the cells of the 

 hypha 3 of the parasite (on wheat), and believes that these are the 

 so-called nuclei of former writers. Similar corpuscles are found in 

 the cells of the host in the infected regions, but never in normal tissues. 

 The author agrees with Marshall Ward and Klebahn in regarding 

 Eriksson's " special corpuscles " as exogenous suckers, i.e., as simple 

 suckers thrust by the mycelium filaments into the interior of the host- 

 cells. The discovery of the metachromatic bodies may be the means of 

 throwing new light upon the whole subject. 



Movements of Plasmodia. f — V. Vouk publishes the results of his 

 investigations concerning the rhythmic streaming of the protoplasm of 

 Plasmodia. The author concludes that this streaming is a rhythmic 

 phenomenon consisting of two movements, viz., a progressive and a 

 retrogressive movement, and as a general rule the progressive streaming 

 is of longer duration than the retrogressive one. The duration of the 

 rhythmic movement has a certain constant value for each particular 

 Plasmodium, but this value is only constant for the main stream ; the 

 additional side streamings at the beginning and towards the end of the 

 phenomenon are subject to continual alterations. This fixed value 

 increases with the growth of the plasmodium. The rhythmic move- 

 ment may be disturbed by external mechanical means, e.g., shaking, the 

 disturbance being: made evident by the increase or decrease of the 

 duration of rhythmic movement. 



Chondriosomes in Plant-cells. £ — <J. Lewitzky has found in the 

 cells of the root of Pisum sativum and in certain meristematic tissues of 

 Asparagus officinalis bodies which appear t<» correspond with thechondrio- 



* Comptes Rendus, clii. (1911) \>\>. (112-15. 



t SB. Akad. Wiss., cxix. (1910) pp. 853-7C (1 pi. and 3 figs.). 



X Ber. Deutsch. Bot. Gesell., xxviii. (1911) pp. 538-16. 



2 I 2 



