Sect. XXXIX. i.i. GENERATION. ' 379 



petual circles towards the fide affected, in order to get a more 

 accurate view of objects ; for the fame reafon as in fquiriting 

 the affected eye is turned away from the object: contemplated. 

 Sheep in the warm months keep their nofes clofe to the ground 

 .to prevent this fly from fo readily getting into their noflrils. 



The liquor amnii is fecreted into the womb as it is required, 

 not only in reipect to quantity, but, as the digeftive powers of the 

 fetus become formed, this fluid becomes of a different confid- 

 ence and quality, till it is exchanged for milk after nativity. 

 Mailer. Phyfiol. V. I. In the ^gg the white part, which is 

 analogous to the liquor amnii of quadrupeds, confifts of two 

 diftinct parts j one of which is more vifcid, and probably more 

 difficult of digeftion, and more nutritive than the other ; and 

 this latter is ufed in the laft week of incubation. The yolk of 

 the egg isa (till ftronger or more nutritive fluid, which is drawn 

 up into the bowels of the chick juft at its exclufion from the 

 fhell, and ferves it for nourifhment for a day or two, till it is 

 able to digeft, and has learnt to choofe the harder feeds or grains, 

 which are to afford it fuftenance. Nothing analogous to this 

 yolk is found in the fetus of lactiferous animals, as the milk is 

 another nutritive fluid ready prepared for the young progeny; 

 it is alfo a curious circumftance, that the firft milk of female ani- 

 mals after parturition is much thicker, like the yolk of egg y and 

 much more coagulable, than that which is fecreted after a few 

 days, when the digeflive powers of the offspring are become 

 ftronger. 



The yolk therefore is not neceffary to the fpawn of fifh, the 

 eggs of infects, or for the feeds of vegetables ; as their embry- 

 ons have probably their food prefented to them as foon as they 

 are excluded from their fhells, or have extended their roots. 

 Whence it happens that fome infects produce a living progeny 

 in the fpring and fummer, and eggs in the autumn ; and fome 

 vegetables have living roots or buds produced in the place of 

 feeds, as the polygonum viviparum, and magical onions. Sec 

 Eotanic Garden, p. ii. art. Anthoxanthum. 



There feems however to be a refervoir of nutriment prepared 

 for fome feeds befides their cotyledons or feed-leaves, which may 

 be fuppofed in fome meafure analogous to the yolk of the egg. 

 Such are the faccharine juices of apples, grapes, and other fruits, 

 which fupply nutrition to the feeds after they fall on the ground. 

 And fuch is the milky juice in the centre of the cocoa-nut, and 

 part of the kernel of it ; the fame I fuppofe of all other monoco- 

 tyledon feeds, as of the palms, grades, and lilies. The milky 

 juice in the centre of the cocoa-nut feems curioufly to refemble 

 the chyle of animals, as it contains oil difFuted with mucilage 



zn4. 



