390 



SCIENCE 



[N. S. Vol. XLVI. No. 1190 



which we deem entirely superfluous. We fail 

 to discern the purpose served by pictures of a 

 " graduated cylinder," a " Beaker," a " burette 

 and rubber tubing," a " specimen jar," " small 

 wooden tables," a " casserole," a " scalpel," a 

 " hemostat," an " evaporating dish," or of 

 clamps, forceps, screws, scissors, oxygen tanks, 

 hand bellows, bottles for holding stock solu- 

 tions, and similar common utensils with which 

 every student and laboratory boy becomes fa- 

 miliar as soon as he enters the class-room. 

 Such illustrations could be obtained at a much 

 less expense, if need be, from any laboratory 

 supply dealer, by writing for an illustrated 

 catalogue. 



Barring the unnecessary mass of subordinate 

 detail in the text and illustrations, Jackson's 

 treatise has certain admirable features. The 

 style of the author bespeaks his intense ear- 

 nestness of purpose and interest in the sub- 

 ject. The descriptions of his original or im- 

 proved methods are often admirable and il- 

 luminating. A number of experiments are de- 

 scribed which are not found in the ordinary 

 text-book. Among these may be mentioned 

 especially experiments on the eyes, intra- 

 tracheal insufflation, elaborate and newer meth- 

 ods of anesthesia, oncometric and other ex- 

 periments on the spleen and other organs, 

 methods for the study of esophageal, vesical 

 and uterine contractions, and the author's 

 chef d'oeuvre — his ingenious methods of study- 

 ing pulmonary conditions, namely, pulmonary 

 circulation, pulmonary pressure, and the con- 

 tractions of bronchioles. Altogether, Jack- 

 son's " Pharmacology " is a unique and inter- 

 esting work and will be found helpful by the 

 pharmacologist, especially in the execution of 

 some particular kind of work. 



David I. Macht 



Phakmacological Laboratory, 

 Johns Hopkins University 



APHIS IMMUNITY OF TEOSINTE-CORN 

 HYBRIDS 



Certain properties and functions are pos- 

 sessed by some plants and animals providing 

 them exemption from disease. The use of the 

 word disease as applied to plants is sometimes 



restricted to bacterial and fungous parasitism 

 and its effects. It is also sometimes applied 

 to disorders brought about by various forms 

 of malnutrition, including attacks by insects 

 and other low forms of animal life. 



.When the favorable conditions of life are so 

 seriously interfered with by any agency, so that 

 the life of a part of a plant or of the whole plant is 

 threatened, we recognize disease in that plant. 



When a plant is able to repel such devas- 

 tating forces, more or less completely, it is 

 said to possess corresponding degrees of total 

 immunity. 



Plants and animals are also subject to dep- 

 redatory attacks of small animal life, parasitic 

 in nature, but not producing what is ordinarily 

 conceded as organic disease. Certain individ- 

 uals repel or resist such depredations and it 

 seems proper to call this phenomenon im- 

 mimity. 



It is with a behavior belonging to the last- 

 named category that this account is concerned. 

 The appearance of an instance of total im- 

 munity of any kind in an economic plant or 

 animal seems eligible to record, and especially 

 when the immunizing factor is hereditary. 



During the early summer of 1913 there were 

 grown in a greenhouse four short rows of Fj 

 or iirst generation hybrid plants coming from 

 seed produced by fecundating teosinte, Eu- 

 clanea mexicana with pollen of yellow dent 

 corn, Zea indentata.^ In the same bed, and 

 immediately adjoining the hybrid rows, were 

 grown one row of the parent strain of teosinte 

 on the one side and four rows of the parent 

 strain of corn on the other. 



1 Teosinte and corn are both members of the 

 grass family, but are classed in different genera. 

 They hybridize freely with each other, although thi 

 teosinte is decidedly grasslike in appearance pro- 

 ducing small two-rowed fruiting spikes in marked 

 contrast to ears of dent corn. The first hybrid 

 generation is intermediate in structure between the 

 two parents, but more nearly resembling the teo- 

 sinte in tillering profusely and being tall, slender 

 and foliaceous. The hybrid ears are also small, 

 fitting rigidly into a cavity of an internode of the 

 rachis which disjoints readily at maturity, but 

 succeeding generations produce some larger fruit- 

 ing spikes more like the dent-corn parent. 



