251 



it may even be said that that this is not tlie most efficacious defence. 

 Further proof of this point will be published in a subsequent paper. 



A typical case is that of Bacillus llparis. The micronucleocytes 

 in the blood of larvae of any species show a remarkable affinity for this 

 bacillus; the envelopment begins soon after inoculation ; the microbes 

 are not seized by the })seudo podia of the cells ; at first they attach them- 

 selves to the surface of the micronucleocyte, the protoplasm degener- 

 ates by their contact and the microbes then penetrate into the cell and 

 become directly incorporated with the protoplasm. The influence of 

 the protoplasm on the incorporated bacillus is nil ; its vitality is not 

 even impaired after a prolonged sojourn in the cell. When the 

 accumulation of bacilli is large enough the cell becomes disorganised ; 

 this is frequently the cause of death in larvae, even those that are 

 most resistant to microbe infection. 



Larvae that do not generally show any resistance to infection, such 

 as those of Pieris brassicae and Vanessa urticae, are very susceptible 

 to the action of the bacillus and yet the micronucleocytes and 

 also the other elements of the blood actively phagocytose it. If the 

 temperature is low the larvae resist indefinitely, but if the temperature 

 rises the microbes innnediately nudtiply in the blood and cause the 

 death of the larvae. A number of entomophytous microbes act in a 

 similar manner to B. liparis ; enveloped in large numbers by the 

 micronucleocytes they become parasitic on the cells and are thus patho- 

 genic to their host. If the number of microbes injected is small the 

 micronucleocytes tolerate their presence, and if the temperature is 

 low, the infection does not become generalised. In any case, it is 

 difficult to consider the envelopment of the microbes as a defensive 

 reaction on the part of the insect. 



The most typical cases of innuunity, those in which the insect is 

 resistant to the inoculation of a large mass of microbes, does not seem 

 to be in any way due to phagocytosis. The case of B. nielolonfhae 

 non-Uquefadens /3 has already been studied ; a certain number of 

 other bacilli seem to behave in the same way, e.g., B. melolonthae non- 

 liquefaciens y, B. piens non-liquefaciens a and B. hoplosternus ; it is 

 hoped that experiments will decide this point in the near future. 



It is noticeable that the larvae that demonstrate the most remark- 

 able cases of innnunity are precisely those in which the reaction of 

 karyokinesis appears most regularly and most strongly. This seems 

 a strong indication, if not a proof, that the most active imuimiity is 

 not due to phagocytosis alone, but to humoral or cellular reactions, the 

 nature of which has not yet been definitely determined, 



L'Utilisation industrielle des Sauterelles comme Engrais dans I'Uruguay. 



— Ball. Agric. Alger. Tun. Maroc, Algiers, xxvi, no. 1-2, Jauuarv- 

 February 1920, pp. 25-26. [Eeceived 6th April 1920.] 



In Uruguay experiments with locusts dried in ovens or by the sun 

 show that a product can be obtained which may be employed in several 

 ways. 



As a fattening food for domestic animals it has a liigher value than 

 oil-cake. As a fertiUser, particularly in extensive cultivation, it is 

 richer in nitrogen and phosphoric acid than dried blood or powdered 

 meat guano. The grease it contains can be used as a lubricant. 



