4 RAINEY, ON STARCH GRANULES. 



was prepared from potatoes which had been kept nearly a 

 year. I have dwelt upon this form, as appearing to me rather 

 singular that it should not have been observed by more 

 botanists j perhaps if it had been sought for as diligently as 

 the granules in pairs its existence would have been more 

 generally noticed. This observation may serve as a hint in 

 the examination of other structures in which the division of 

 cells into two is said to take place as in cartilage. I am 

 perfectly aware that triplets with granules of nearly equal 

 size will, as a matter of course, be less frequent than similar 

 pairs. Those represented in figs. 2 and 3 are a modification 

 of the dumb-bell shape, which is seen much better in the 

 smaller granules which unite before they lose their spherical 

 form. These may be well seen in thin transverse sections of 

 the very young houseleek, Sempervivum tectorum. 



Figs. 6 and 7 are representations of a description of starch 

 granule, called by physiologists " compound granules." 

 These have been variously explained by different authors, but 

 in all cases which have come under my notice the explanation 

 of the central part of such granules has been made dependent 

 upon some assumption which has been irreconcilable with 

 the principle of explanation applied to the peripheral part.* 



Fig. 6 is taken from Criiger's plate, as copied in the ' Micro- 

 scopical Journal.' This copy, I may observe, is not intro- 

 duced here, from my being unable to obtain similar specimens 

 myself. They are frequent enough in the kind of starch 

 called "tous les mois," but the facts very well shown by 

 these drawings will have more weight as coming from diffe- 

 rent and independent observers. These granules consist of 

 two or more simple granules, each having its own lamellae, 

 and the whole surrounded by common lamellae. 



Fig. 8 is an accurate representation of two globules of 

 carbonate of lime from the calcifying shell of the oyster. 

 There is so striking a resemblance between the structure of 

 these and those marked fig. 6, that no one would question 

 their laminated structure and their union as being otherwise 

 than the result of a similar cause, and very likely to be pro- 

 duced in both cases, either by the layers of increment 

 deposited on the inner surface of a cell-wall, or by the layers 

 deposited around a centre or nucleus. Such was the con- 

 clusion arrived at respecting these bodies by physiologists 

 before it was shown by me, in 1857, that exactly such 

 forms as that represented in fig. 8 could be produced 

 artificially, and that there were sufficient grounds for be- 



* See these treated of in the April number of 1854 of the 'Quarterly 

 Journal of Microscopical Science,' by Dr. Allman and H. Criiger. 



