Ihe American Naturalist. 



[\pril. 



little that is really new being added, but most facts being correctly 

 stated. The names of many of the species, however, are changed for 

 reasons which would not be recognized as good even by the most ultra 

 radical. For example Cystopus candid™ is changed to C. capsellw E. 

 H. because the fungus is said to grow mostly on Capsella and every 

 fungus should be named as far as possible from the host it infests. In 

 like manner Cystopus cubicus becomes C. compositarum E. H. ; Phyto- 

 phthora infestans, P. solani E. H. ; Peronospora sparsa, P. rosce E. H., 

 etc. In the same way the author puts his initials after many old genera 

 e. g., Phytophthora and Peronospora, or substitutes other names, e. g. 

 Zoospora E. H. for Plasmopara, because he concieves the name to have 

 been originally employed in a different sense from that in which it is 

 now used or in which he employs it. The other idea running through 

 the book and occupying at least a third of it is that bacteria originate 

 from plastids developed inside of the cells of fungi, and that we shall 

 never make any progress in the study of animal and plant diseases due 

 to bacteria until we determine from just what fungi they originate. 

 The potato rot, for example, is due to bacteria developed from the 

 broken down mycelium of the fungus Phytophthora infestans. 



"If now one keeps for a long time in observation under the micro- 

 scope such an escaped mass of plasma [from the mycelium or conidia 

 of Phytophthora] one beholds, just as in the cases already mentioned 

 by us, the freeing of the plastids, their change into micrococcus and 

 the elongation, division, etc. of these." (P. 82). In Peronospora fica- 

 riw also " the origm of the microorganisms is unquestionable, but until 

 now I have not been able to follow them further. These organisms are 

 visible in a fresh section in the interior of the leaf tissue of the host." 

 (P. 134.) The converse of this proposition is also true i. e. that under 

 certain conditions bacteria change back again into the original fungus, 

 the growth of certain yeast cells into mycelium being cited as a case in 

 in point. " If these [bacteria] arise from definite fungi by the finally 

 free development of the plastids, it must also come to pass that the 

 micrococcus, which is the first product of the freed plastids, will again 

 give rise to the higher fungous form from which it originated. Of this 

 the first well known and precise example is the history of the develop- 

 ment of the beer yeast." (P. 105.). The author who is a graduate of 

 one of the German Universities, formerly held a chair of botany in one 

 of them, and has been writing books similar to this one for the last 30 

 years claims to have seen the change from fungous plastids inside of 

 myceha or spores into genuine free swimming bacteria, rods and cocci. 

 This change is difficult to bring about artifically, requiring long watch- 



