INTEGRATION OF AGGREGATIONS 97 



physics. These workers believe they have demonstrated that rapidly 

 growing plant and animal tissues give off radiations which are able to 

 stimulate other tissues completely separated from the so-called 

 "senders" by being inclosed in quartz tubes so that these "detectors" 

 show a decided increase in mitoses on the radiated half as compared 

 with the non-radiated part of the same stem. 



A favorite experiment consists in placing a moist onion root, 

 attached to part or all of the bulb from which it grew, into a small 

 tube made of quartz. One or more onion roots from different bulbs 

 are introduced into open-ended glass tubes and are also kept moist. 

 The former is to be the detector; the latter, the sender. The sender 

 is carefully centered so that its growing root tip points directly to- 

 ward and at right angles to the detector root, and is allowed to re- 

 main so for from i to 2| hours. The detector is then marked with 

 India ink on the side away from the sender and is killed in an ap- 

 propriate fixing-solution and sectioned. In fixed and stained sections 

 the number of mitoses on the exposed and non-exposed sides are 

 compared. Most of the work reported to date shows uniformly a 

 greater number of mitoses on the exposed side ; the work of Rossman 

 (1928) is an exception. These are believed to have been induced by 

 the action of mitogenetic rays. Definite but conflicting wave-lengths 

 have been announced for these rays. 



This field needs further clarification before we can begin building, 

 with a sense of security, upon the suggestions opened by this work. 

 If the presence and importance of mitogenetic rays are finally es- 

 tablished, we shall then have to inquire carefully whether or not we 

 have similar subtle means of group integration in the field of bio- 

 physics which may help us resolve the problems in social and sub- 

 social behavior that are epitomized by Maeterlinck's phrase "the 

 spirit of the hive." 



