BOOKS AND CURRENT LITERATURE 



Cytology of Rhodochytrium.- — Several years ago in a preliminary 

 paper, Atkinson reported the presence in North Carolina of Rhodo- 

 chytrium spilanthidis Lagerh. on the ragweed, Ambrosia artemisiaefolia. 

 This remarkable parasite was discovered in 1889 near Quito, Ecuador, 

 on a species of Spilanthes'. A peculiar interest centers around this 

 form because of the transitional position which it occupies in our phylo- 

 genetic scheme. It shows a relationship on the one hand to certain 

 protococcoid algae, as Phyllobium, and on the other to some of the 

 chytridiaceous fungi, as Synchytrium. 



Griggs 1 has recently published a highly interesting as well as exhaus- 

 tive consideration of the life history and cytology of a Rhodochytrium. 

 The retort-shaped cysts appear as bright red specks within the tissue' 

 of the leaves and stems of ragweed. Rhizoids, basal and lateral, extend 

 into the vascular tissue especially the phloem elements. The cysts, 

 which are formed during May and June, become zoosporangia, producing 

 zoospores of the algal type. The zoospores rarely conjugate except 

 when confined to small amounts of fluid. Those which come to rest 

 upon the host form germ tubes, which can penetrate the tissues at 

 any point. As a result of the infections, other temporary sporangia 

 are formed or, if it is later in the season, July or August, resting sporan- 

 gia are developed instead. These resting sporangia differ from the 

 temporary sporangia in that their walls are thicker and they remain dor- 

 mant till the following season. The walls of the resting sporangia 

 consist of three layers, the outer of which is formed first. The two 

 outer layers, which are composed of cellulose, constitute the exospore, 

 while the endospore consists of a layer of non-cellulose material. 



Owing to the fact that Rhodochytrium has no chlorophyll, special 

 consideration is given to starch formation. The starch grains, so far 

 as could be determined, are formed in the cytoplasm without the inter- 

 vention of plastids, pjo-enoids or other specialized protoplasmic bodies. 

 There is no evidence, even, of the presence of microsomes as found by 



1 Griggs, R. F., The Development and Cytology of Rhodochytrium. Bot. 

 Gaz. 53: 127-173. pis. 11-16, 1912. 



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