46 LECTURE I. 



agonal form, and within them one or two nuclei (Fig. 1). 

 Towards the cortex (corky layer) the cells are four-sided, 

 and the farther one proceeds outwards, the flatter do 

 they become ; still, nuclei may be distinctly recognised 

 in them also. Wherever the so-called cells come in con- 

 tact, a boundary line may be recognised between them ; 

 then comes the thick layer of cellulose, in which fine 

 streaks may be observed ; and in the interior of the 

 capsular cavity you see a compound mass, in which a 

 nucleus and nucleolus may be easily distinguished, and 

 after the application of reagents the primordial utricle 

 also makes its appearance as a plicated, wrinkled mem- 

 brane. This is the perfect form of a vegetable cell. In 

 the neighbouring cells lie a few larger, dimly lustrous, 

 laminated bodies, the remains of starch (Fig. 7, c). The 

 next object is of importance in my eyes, because I shall 

 afterwards have to refer to it when instituting a com- 

 parison with new formations in animals. It is a longi- 

 tudinal section of a young lilac bud, developed by the 

 warm days we have had this month (February). In the 

 bud a number of young leaves have already begun to 

 develop themselves, each composed of numerous young 

 cells. In these, the youngest parts, the external layers, 

 are composed of tolerably regular layers of cells, which 

 have a rather flat, four-sided appearance, whilst in the 

 internal layers the cells are more elongated, and in a 

 few parts spiral vessels show themselves. Especially 

 would I call your attention to the little out-growths 

 (leaf-hairs Blatthaare), which protrude everywhere 

 along the border, and very much resemble certain ani- 

 mal excrescences, e. g., in the villi of the chorion, where 

 they mark the spots at which young, secondary villi 

 will shoot out. In our preparation, you see the little 

 club-shaped protuberances, which are repeated at cer- 



