306 



SCIENCE 



[N. S. Vol. XXXIII. No. 843 



types, principally from culture animals, have 

 been added, including Amaha lacertce, A. dip- 

 loidea, Entamceha muris, E. teiragena, Tricho- 

 monas muris, Laniblia (and Octomitus) 

 muris, Leucocytozoon ziemanni, Proteosoma 

 prwcox and Balantidium coli. 



The plan of treatment is comprehensive, in- 

 cluding general introductions to each group, 

 and detailed accounts of the morphology and 

 life history of each of the forms discussed to- 

 gether with directions for securing, control- 

 ling, cultivating and preparing the material 

 for study. Illustrations often in color, illus- 

 trate the various stages and assist materially 

 in the interpretation of laboratory material. 

 Brief bibliographies of a few pertinent papers 

 are appended. 



It is to be regretted that the student of 

 Babesia canis is left uninformed of Nuttall's 

 work, that Fantham's work as well as Schel- 

 lack's on spirochsetes is not cited and that the 

 sexual phase of the cycle of Trypanosoma 

 lewisi is described as reported by Prowazek in 

 Hcematopiniis without any hint as to the re- 

 serve with which his conclusions on this point 

 have been generally received. This lack of 

 caution is all the more regrettable in the light 

 of Minchins's experiments with fleas as car- 

 riers and Doflein's recently published results 

 of his experimental cultures and his conclu- 

 sions as to the necessity of caution in inter- 

 preting stout and slender forms as sexual 

 gametes and their conjunction as conjugation. 



No chapter on technique of parasite flagel- 

 lates is complete either historically or tech- 

 nically without calling the student's attention 

 to the culture methods of Novy and MacNeal. 

 Such omissions as these are hardly to be con- 

 doned by the fact that the author is writing 

 primarily for the German student. 



The figures are often original and are uni- 

 formly excellent. The condensed but compre- 

 hensive and lucid account of the significant 

 features of the structure and life history of 

 the important pathogenic and parasitic types 

 available for laboratory use will be of greatest 

 assistance to the student in this diificult field. 



Charles A. Kofoid 



Bekkelet, Cal. 



TEIPBENTLMETHTL 

 Since modern methods of formulation were 

 established, organic chemists have been able 

 to represent the many thousands of com- 

 pounds, whose constitution has been eluci- 

 dated, by formulas in which the carbon atoms 

 are always tetravalent. The single exception 

 was carbon monoxide, CO, in which the car- 

 bon is necessarily represented as being bival- 

 ent. 



In view of these facts it was natural that 

 Gomberg's discovery of " triphenylmethyl," 

 (CoH5)50, should arouse widespread interest, 

 because, if it be correctly formulated, the car- 

 bon atom marked * is trivalent. During the 

 ten years which have elapsed since Gomberg's 

 discovery was first announced, a very large 

 amount of work has been carried out in order 

 to elucidate the true nature of triphenyl- 

 methyl. The most important contributions, 

 which are summarized below, have been made 

 by Gomberg himself, by A. E. Tsehitschibabin, 

 A. von Baeyer and more recently by W. 

 Schlenk' and his co-workers in Baeyer's lab- 

 oratory. 



" Triphenylmethyl " is prepared by the ac- 

 tion of certain metals, such as zinc, on tri- 

 phenylchloromethane, (CjH5)sCCl; the metal 

 simply removes the chlorine atom. " Tri- 

 phenylmethyl " exists in two forms, a white, 

 solid modification, which is relatively stable, 

 and a soluble yellow form exhibiting very 

 great chemical activity. This colored variety 

 has a molecular weight corresponding to the 

 simpler formula, (CgH^jC. 



As regards the colorless material, the facts 

 pointed to its being- hexaphenylethane, 

 (C,H,)3C-C(0,H,)3, but many chemists hesi- 

 tated to accept this view, chiefly, perhaps, for 

 the following reasons. The substitution of 

 phenyl groups for hydrogen in hydrocarbons 

 results, in general, in an increase in the sta- 

 bility of the product, consequently, in passing 

 from ethane, CH.-CH., to hexaphenylethane, 

 (C,H,)3C-C(C.H,)3, we should expect to ob- 

 tain an inert substance, but we find that the 

 '■ hexaphenylethane," mentioned above, is so 

 unstable that its mere solution, at the ordi- 



ifier. d. chem. Oes., 43, 1753, 3541, 1910. 



