30 



SCIENCE 



[N. S. Vol. XXXVI. No. 914 



will be quite misleading, as no account is 

 taken of the relative cost of the articles — 

 surely an important matter in these days — ^but 

 also the fact must be borne in mind that in 

 the free consumption of cacao-products a no- 

 table amount of an alkaloid is introduced 

 while in standard foods no such ingestion 

 occurs. Notwithstanding the high calories 

 and even high protein content of cacao-prod- 

 ucts we should err in regarding them as more 

 than beverages and confections. 



We are informed that while Theohroma 

 cacao is the principal source of cacao-prod- 

 ucts, several other species contribute a not 

 important share. It is satisfactory to note 

 that while commercial conditions necessitate 

 the use of the term " cocoa " as a name for 

 the marketed products, the author emphasizes 

 the fact that the correct title is " cacao " and 

 uses this when speaking of the raw materials 

 and also the separated fat, which is (very 

 properly) termed " cacao-butter." Inciden- 

 tally another important point is noted, namely, 

 that the oil from the fruit of the Oocos nuci- 

 fera should be termed " coconut oil " and not, 

 as is often done, " cocoanut oil." For thus 

 aiding in correct orthography Mr. Whjrmper 

 deserves thanks. 



The methods of cultivation, ingathering and 

 curing are given in great detail, illustrated 

 with many fine full-page photogravures. The 

 machinery employed in manufacturing the 

 several commercial preparations is also illus- 

 trated and described. Of course, the cacao 

 plant is subject to diseases, but it is specially 

 interesting to note that in many places its 

 successful cultivation requires the association 

 of other trees for shade, and that these latter 

 sometimes communicate their diseases to the 

 cacao nut. In this connection it is worth 

 pointing out that it has been long known that 

 sandalwood trees do not thrive when grown by 

 themselves, and it was supposed that this is 

 due to need of shade, but it has lately been 

 proved by the investigations in India that 

 sandalwood is a partial root-parasite. In 

 Trinidad a particular luguminous tree is so 

 commonly used as a shade for cacao that it is 

 known as " Mother of Cacao." 



The food chemist will find in this work a 

 vast amount of important and interesting 

 technologic and analytic data. The commer- 

 cial forms of " cocoa " and " chocolate " are 

 fully explained both as to preparation, com- 

 position, analytic examination and adultera- 

 tion. Over one hundred pages are devoted to 

 these topics, and the bibliography, a summary 

 of which is given separately, covers a very 

 wide range. 



No important typographic errors have been 

 noted. On p. 65, the date for the reference to 

 Chem. Zeit. should apparently be 1897, instead 

 of 1887. 



The book is a timely and valuable contribu- 

 tion to the literature of an important topic. 



Henry Leffmann 



SPECIAL ARTICLES 



ELM LEAF CURL AND ■VVOOLLY APHID OF THE 

 APPLE 



It was with considerable astonishment while 

 working over some elm aphids several winters 

 ago that I found that I was unable to separate 

 on structural characters certain collections of 

 Schizoneura americana (causing and inhabit- 

 ing elm leaf curl) from certain collections of 

 Schizoneura lanigera (the troublesome woolly 

 aphid of the apple). It seemed absurd to 

 suppose that a species under such constant 

 observation as the woolly aphid of the apple 

 could be masquerading on our elms all these 

 years without biological evidence of the fact 

 having been chanced upon long ago. 



However, the guess based on structural evi- 

 dence, wild as it seemed, was worth following 

 up and field observations were made during 

 the next seasons. Spring migrants were ob- 

 served to desert the elm leaves in the early 

 summer, and fall migrants to leave the apple 

 branches in the fall, but no conclusive data as 

 to the destination of either were obtained in 

 the field. Both migrations covered a rather 

 extended time and the situation was especially 

 complicated by the continuous presence of 

 apterous forms on the apple (either on branch 

 or root) all the year and of " rileyi " on the 

 trunks of young elms during the summer. 



