156 GERMINATION OF OILY SEEDS. 



produced by transitory causes, the shells next season resuming 

 their normal form. An interesting and instructive collection might 

 be made from a single pond, continued over a series of years. 

 This has been done, to a small extent, by our friend, Mr. Madison, 

 and serves to show that slight alterations in the environment, so 

 slight as to be imperceptible to the conchologist, still leave their 

 impress upon the shells. 



Mr. Purves describes and figures a specimen obtained by him 

 on Belford Moor, Northumberland, which had a regular keel 

 round the upper part of the whorl, giving the shell an appearance 

 very unlike the normal form of the species, This was, no doubt, 

 due to an injury to the mantle of the animal. 



Dr. Brot mentions that in a pond in the environs of Geneva a 

 number of abnormal forms of this species were obtained. The 

 pond swarmed with Hydra viridis, which he fixed upon as the 



cause of the variation, being confirmed in 

 this opinion by the disappearance simultane- 

 ously of the Hydra and the abnormally 

 formed shells. 



During March, 1883, I collected many 

 specimens in a pond at Allerton Ings, the 

 Fig. 10. -Abnormal Shell, majority of them being deformed, the cause 

 of which I ascribed at the time to superabundance of food. 



The Germination of Oily Seeds. — According to M. Leclerc 

 du Sablon, the reserve substance of oily seeds, whether they are 

 stored up in the embryo or in the endosperm, consists chiefly of oil 

 and aleurone ; starch is but rarely found in them. In the species 

 examined, the proportion of oil decreases regularly during the period 

 of germination. By the action of a diastase, the oil is transformed 

 into fatty acids without any separation of glycerin. During germi- 

 nation these fatty acids, instead of accumulating, are themselves 

 transformed into carbo-hydrates, especially into those belonging to 

 the group of saccharoses. This saccharose is again converted, by 

 the action of a diastase, into glucose, which is directly assimilated 

 by the plant. Starch is also temporarily present as an intermediate 

 product between oil and glucose. Starch and oil, as reserve sub- 

 stances, give rise to the same assimilable products during the ger- 

 mination of the seed. — Bonnier's Revue Generale de Botanique. 



