Makch 21, 1913] 



SCIENCE 



439 



CONCLUSION 



I believe the facts mentioned in this 

 address show that those animal cells or 

 organs which lend themselves to exact 

 measurements of osmotic changes obey the 

 law of Avogadro-van 't Hoff, as long as 

 they are normal or alive : i. e., they neither 

 absorb nor lose water if put into solutions 

 of any kinds of sugar or neutral salts 

 which are equi-molecular with the blood; 

 that they absorb water in solutions of 

 lower osmotic pressure, lose water in solu- 

 tions of higher osmotic pressure. If the 

 law of Avogadro and van 't Hoff is correct 

 (which nobody doubts), this behavior of 

 the tissues is the expression of the applica- 

 bility of this law to the exchange of water 

 between tissues and liquids of the body. 



It does not often happen in biology that 

 we are able to reduce life phenomena to a 

 fundamental physico-chemical law to such 

 an extent that we can not only predict the 

 results qualitatively, but also quantita- 

 tively, as is the case in the application of 

 Avogadro 's law to the exchange of water 

 between tissues and the liquids of the body. 



If anybody wishes to supplant the law 

 of Avogadro he must be able to offer a the- 

 ory which allows a still closer approxima- 

 tion between calculated and observed re- 

 sults than is the case in the experiments on 

 the absorption of water by animal cells or 

 tissues. No such theory has thus far been 

 offered. 



Jacques Loeb 



The Eockepeller Institute 

 POE Medical Beseabch 



THE SPREAD OF THE BROWN-TAIL AND 

 GYPSY MOTH 



For several years Massachusetts has been 

 spending large sums of money in fighting the 

 brown-tail and gipsy moths. These insects 

 have spread westward in their devastating 

 course and are now recorded from a point 



not far distant from the eastern boun- 

 dary of New York. In February a con- 

 ference was called in Boston by the state for- 

 ester of Massachusetts for the purpose of 

 bringing together not only those actually en- 

 gaged in the fight with the gipsy and brown- 

 tail moths, but those who are sure to be con- 

 cerned in the near future. The New York 

 State College of Forestry at Syracuse Uni- 

 versity is investigating the work of these in- 

 sects and Dr. M. W. Blackman, forest ento- 

 mologist of the college, was its representative 

 in the conference in Boston and is ready to 

 take up the fight against these insects when 

 they appear in this state. 



Interesting facts were brought out at this 

 conference as to the spread of the gipsy moth. 

 It is very certain that New York and other 

 states about Massachusetts will soon be 

 reached by these destructive insects and that 

 unless more effective means are taken they 

 will destroy not only forest trees but shade 

 and ornamental trees over large sections of 

 the state. As shade tree pests these insects 

 can be controlled by spraying and destroying 

 egg clusters, but these methods are used only 

 at considerable expense and must be continued 

 indefinitely. It seems probable that as soon as 

 the parasites and diseases introduced from 

 abroad which work upon and destroy these in- 

 sects have become fairly established that they 

 will aid man greatly against future serious 

 outbreaks. 



The gipsy moth problem of the future in 

 the state of New York is a forestry problem, as 

 the insect can not be fought in the forest by 

 spraying but must be controlled and eventu- 

 ally eliminated by proper methods of forest 

 management. Certain trees, such as the oak, 

 willow and birch, are apparently more favor- 

 able and often seem necessary for the develop- 

 ment of the caterpillars of the moths. Meth- 

 ods of forest management can be used which 

 will remove these trees from the forest and 

 thus destroy the most favored food of the 

 pests. With these methods of proper forest 

 management must go strict quarantine against 

 lumber, eordwood and nursery products 

 shipped in from infested areas. Some effort 



