ACACIA SPRJEBOCEPHAI/A AND CECJROPIA PELTATA. 403 



embedded initarow of spherical bodies; they are about '0032 inillim. 

 in diameter, and of a dingy yellow colour. As the oil is formed they 

 disappear; but their pigment, no doubt, gives the golden tint to the 

 young food-bodies, and its subsequent absorption causes the change 

 to dull white observable in the older ones. There can be no doubt 

 that they are chlorophyll-bodies which have never developed beyond 

 their early yellow stage; and, from the manner in which the oil takes 

 their place, I believe that they are actually converted into that sub- 

 stance. This phenomenon is not abnormal ; for oil is formed in the 

 chlorophyll-bodies of Allium cepa*. Again, chlorophyll-bodies may 

 be absolutely converted into what should be normally a contained 

 product, as in the case of the starch-grains mentioned by Sachs f. 

 It is not meant that all the oil is produced by the transformation 

 of chlorophyll ; it is doubtless also secreted as droplets in the pro- 

 toplasm. Indeed the latter mode of formation is far more in accord- 

 ance with the supposition that the food-bodies were originally glan- 

 dular ; for Hanstein % has shown that most resins and balsams are 

 secreted as minute drops in a vacuolated protoplasm of the gland- 

 cell. It also corresponds with the formation of animal secretions^ 

 e. g. of the oil in the sebaceous-gland cells. On the other hand, 

 the transformation of the chlorophyll into oil may perhaps cor- 

 respond with another form of secretion of the same substance in 

 the animal kingdom, viz. in the mammary gland. In his paper § 

 on the mamma, Dr. Creighton shows that the formation of fat in 

 a mammary cell is essentially a process of endogenous cell-for- 

 mation, the old cell giving birth to a new protoplasmic mass which 

 is entirely converted into oil. Now, in reference to the origin of 

 chlorophyll-bodies, Sachs remarks ||, "it can to some extent be 

 compared to the process of free-cell formation ;" so that if I am 

 right in supposing that the chlorophyll is transformed into oil, it 

 will agree with the formation of the fatty part of milk, in its 

 essential feature of being a cell-formation. At the risk of 



■ 



appearing fanciful I may note that the colostrum, or first milk, is 

 yellow from haemoglobin, the respiratory pigment of animal life J 

 and in the same way the young food-bodies are coloured yellow, 

 the respiratory pigment of plant-life. 



* Sachs, ■ Physiologie Vegetale,' p. 354. 



t 'A Text-Book of Botany,' Eng. translat. p. 49. 



X Bot. Zeit. 1868, No. 43. 



§ Reports of the Medical Officer to the Privy Council, 1875, No. vi. p. 171. 



I ' A Text-Book of Botany,' Eng. translat. p. 48. 



