KAKVoKIM.SIS 239 



your idea of the nature of protoplasm. What differences did you find 

 between the cells of yeast and those of green alga .' In what way- do 

 they resemble each other.' Tell the same of cells of protocooens and 

 of apple, or of other material studied. What is a vacuole 1 What 

 does it usually contain .' Name two kinds of movements of protoplasm 

 within the cell-wall, and explain how each may I red. Name 



and describe two movements of naked protoplasm. Tell something 

 of the texture of cell-walls. Whal causes the markings found on cell- 

 walls .' Name live types of markings. Draw two figures to show 

 structure of bordered pits. Make a sketch of spiral, annular, and 

 scalariform markings. Name two methods of cell-multiplication. 

 Describe the process of cell-division. How does cell-budding differ 

 from cell-division! Name two methods of nuclear division. Which 

 is the more common method .' 



Note to Paragraph 393. Karyokinesis (the indirect or mitotic 

 process of nuclear division J is an intricate subject. The details vary 

 in different plants, but tin- essential Btages are as follows: 



During the resting stage the nucleus is surrounded by a very deli- 



i >u t distinct membrane. Within this inclosure i- an intricate i 

 work of colorless [linin I threads bearing very numerous granules, which 

 in stained preparations are highly color..!, and for this reason have 

 received the name chromatin. The network i- Bnrrounded by nuc 

 v :l p, and often incloses within its meshes a large body called the 

 nucleolus. As the time for division approaches the chromatin network 

 changes into a definite, much-coiled, deeply stained ribbon, in which 

 the granular structure is much less noticeable, and this in turn - 

 ments transversely into a number of parts called ehromo The 

 protoplasmic fibrils immediately surrounding the nucleus now grad- 

 ually converge towards two points lying on opposite Bidei of the 

 nucleus and al a slight distance from the membrane. Th iom- 



plished in such a way that n Bpindle of nearly colorless threads is 

 produced, with tin- two previously mentioned points of convi 

 acting a- poles. Meanwhile both He' nuclear membrane and the nu- 

 cleolus have disappeared, but whether these structure ' in 

 the formation of the spindle is yel an open question. Radial 



of protoplasmic threads called a unetimes ur around th" 



poles, and in a few lower plants, a- well aa in most animals, the | 

 i~ occupied by < -mall Bpherioal body termed a ,,,.,.. r i,. 

 steps -o far are known as th" propJ The ohron 



move to th.- equator of 1 1 1 - - spindle, where tie - >" 



a definite manner, forming th" bo called < 



. | . i ich i jmenl splits longitudinal!; . sppai 



