486 SUMMARY OF CURRENT RESEARCHES RELATING TO 



logical examination to see if they cannot be classified in a way that will 

 also express their chemical affinities. Zopf has isolated several new 

 acids, and in some cases he finds that plants looked on as varieties must 

 be treated as species ; thus C. fimbriate/, f . nemoxyna has been made a 

 species by the author because it contains no fumar-protocetrar-acid, such 

 as is found in C. fimbriate/ and others closely allied. 



Mycetozoa. 



•(By A. Loerain Smith.) 



Spongospora Solani.* — T. Johnson publishes a carefully worked out 

 study of this organism, which he considers to be a slime-fungus closely 

 allied to Plasmodiophora. It causes scabs on potato tubers, and in 

 some districts in Ireland it is as injurious to potatoes as finger-and-toe is 

 to turnips. The spores are grouped in balls, comparable to grains of 

 sand, and just visible to the naked eye. When still immature the 

 spore-contents appear as one fairly dense body ; at a more advanced 

 stage they contain six or eight distinct bodies — swarm-spores which 

 escape into the surrounding medium, and serve to propagate the 

 Spongospora. Scabby potatoes when planted produce other scabby tubers ; 

 sometimes the rhizome is affected. Clean seed-potatoes are essential to a 

 healthy crop. Johnson gives advice as to checking or overcoming the 

 disease. 



Existence of Myxomonas Betae.f — This organism was originally 

 described by Brzezinski as a pseudo-myxomycete which lived parasitic- 

 ally on beetroot. The results were questioned by Trzebinski in a 

 later paper, and now by F. C. von Faber, who has gone over the whole 

 ground carefully, and in his summing up says : — " No stage whatever of 

 any myxomycete of any kind could be found in the roots, and it can be 

 stated with absolute certainty that Myxomonas Betce does not exist." 

 Faber gives proofs of his statement ; he finds that what were considered 

 to be zoospores in motion were protoplasmic particles in Brownian 

 motion, or perhaps bacteria that had got into the cultures. 



Dimorphism in a Myxomycete4 — E. Pinoy records further observa- 

 tions on a culture of Bidymium nigripes. With white plasmodia placed 

 in his culture tubes he was able to obtain fructifications in 10 to 20 

 days. Some of the tubes, however, showed a plasmodium that was 

 yellow or orange, others blackish violet. From neither of these did he 

 obtain fructifications, only sclerotia. He tried again by mixing the two 

 plasmodia, and failed ; he then made separate cultures of the two 

 sclerotia, and taking the myxanicebag obtained he mixed a few of them in 

 a third culture tube. Under these conditions he obtained fructifications 

 in 10 or 12 days. Pinoy considers that he is dealing with a form of 

 sexuality, that he has -f and — spores, such as were found by Blakeslee 

 in Mucor, that with one or the other alone there is no fructification, but 

 only when the two kinds are mixed. 



* Econ. Proc. Roy. Dublin Soc, i. (1908) pp. 453-64 (1 pi.). 

 t Ber. Deutsch. Bot. Gesell., xxvi. (1908) pp. 177-82. 

 % C.R. Soc. Biol. Paris, lxiv. (1908) pp. 630-1. 



