June 25, 1920] 



SCIENCE 



641 



the vicinity of Bellingham, State of Wash- 

 ington, U. S. A., having a soil and climate 

 similar to that of the district in Holland 

 just mentioned, and suffering more or less 

 severely from the ravages of Tylenchus dipsaci 

 because this nema is not sufficiently held in 

 cheek by any natural force. We may suppose 

 that in this latter case dipsaci has been intro- 

 duced at Bellingham without the enemies and 

 parasites that hold it in check in the first- 

 mentioned place. The mononchs foimd in the 

 soil of the Holland district feeding upon 

 Tylenchus dipsaci are collected and trans- 

 ported to Bellingham and introduced into the 

 soil. There is good reason to suppose that 

 under the new conditions, finding their food 

 abundant, including the larvae and young of 

 Tylenchus dipsaci, the mononchs will flourish 

 Tylenchus dipsaci in check. 



If it be asked why injurious nomas are 

 transferred from place to place without their 

 enemies being transferred at the same time, 

 the answer is that nemas injurious to plants 

 are often transferred in the interior parts of 

 plants imported in a living condition, and, 

 as already indicated, the mononchs and other 

 predatory nemas are less common in these 

 situations than they are in the adjacent soil, 

 which latter in the course of commerce often 

 is removed from the roots and not shipped. 

 One need only instance the case of bulbs and 

 similar importations to see how much better 

 chance the injurious parasitic nemas have of 

 being imjKjrted than have those nemas which 

 feed upon them. There is also reason to 

 believe that sometimes the parasitic nemas 

 infesting crops are more resistant to im.to- 

 ward conditions, e. g., dryness, than are the 

 predaceous nemas. 



We have at the present time arrived at a 

 stage where logically the next step is to try 

 out the introduction of promising species of 

 mononchs. Efforts of this kind will neces- 

 sarily be somewhat expensive, probably more 

 expensive than the corresponding early efforts 

 to introduce beneficial insects. There can be 

 no doubt, however, that the enormous losses 

 due to plant-infesting nemas fully justify 

 the expenditure of even large sums of money 



in an effort to apply this remedy, more partic- 

 ularly because the remedy, when successful, 

 bids fair to be permanent and self-sustaining. 



After long-continued and intensive studies 

 I am thoroughly convinced that many of the 

 practises evolved in the transfer of beneficial 

 insects can, with appropriate modification, be 

 applied to the nemas. At the present time 

 the greatest drawback in the case of the nemas 

 is the small number of people who are tech- 

 nically competent to make the necessary bio- 

 logical examinations. It is in this respect 

 principally that their introduction will differ 

 from that of the introduction of useful in- 

 sects, for the nema problem is essentially a 

 microscopic one. Though the collection of 

 the nemas from the soil differs entirely from 

 the collection of beneficial insects, the meth- 

 ods have already been brought to such a state 

 that there are no insuperable obstacles. 



The percentage of mononchs in miscella- 

 neous collections of soil-inhabiting nemas 

 taken from various situations is roughly in- 

 dicated by the following figures based on the 

 writer's examinations — in each case of from 

 one thousand to several thousand specimens : 



1. Miscellaneous collection from very small 



quantity of soil taken from the roots of 

 14 species of plants imported from Brazil, 

 6.5 per cent, mononchs. 



2. Sandy soil about the roots of astilbe and 



peony, Holland, 11.6 per cent, mononchs. 



3. Soil from cornfield in New Jersey in 



autumn, the prevailing genus was Mon- 

 onchus. 



4. Sand from Washington filter beds, 96 per 



cent, mononchs. 



N. A. Cobb 

 TJ. S. Depaetment or AaRicuLirrRB 



THE INTERACTION OF ETHYLENE AND 

 SULPHURYL CHLORIDE 



Some time ago,^ while treating suphuryl 

 chloride (SO.CIJ with ethylene gas (C,H^) 

 at room temperature, the writer discovered a 

 reaction quite different from any other which 

 has come under his observation. It was 

 noted that when a fairly strong, steady stream 



1 First observed on Pebruary 28, 1918. 



