APPENDIX 



1. P. 15, Fig. 6. According to Meves (A. m. A., XLVIII. I, '96), the attraction-sphere 

 of the resting spermatogonium of the salamander contains two centrosomes, and these are 

 much smaller than the body figured by Rawitz. I find this to be also the case in Amphiuma, 

 where the attraction-sphere is sharply defined and the centrosomes, though very small, are 

 extremely distinct. 



2. P. 1 6. Conklin (Am. Nat., Jan., '97) states that in cells of the intestinal epithelium 

 of the isopod Porcellio, the nuclear membrane is sometimes absent on one side of the 

 nucleus, and the linin-network here shows an unbroken continuity with the cytoplasmic 

 thread-work. 



3. P. 19. Many recent researches indicate that no general formula can yet be given 

 for protoplasmic structure. The alveolar theory has gained many adherents, yet the opinion 

 is gaining ground that in varying physiological states of the cell protoplasm may undergo 

 more extensive structural changes than was formerly supposed. Flemming himself now 

 admits the existence of alveolar structure in protoplasm (Merkel u. Bonnet, Erg., V., '96), 

 though his conception still differs widely from Biitschli's. He now recognizes: (i) An 

 apparently homogeneous ground-substance ; (2) In many cases this substance is filled with 

 minute vacuoles, giving the alveolar structure of Biitschli; (3) In many kinds of cells, fibres, 

 lying in the ground-substance, and perhaps consisting of rows of microsomes; (4) In some 

 cases separate granules embedded in the ground-substance and many of them certainly 

 preformed in life. Flemming practically abandons his early view that the thread-work or 

 reticulum probably represents the " living substance," and now admits that any or all of the 

 four elements enumerated above may be the substratum of vitality. 



4. P. 27, 1. I (see also p. 246). The large size of the nuclei in embryonic as compared 

 with adult cells was noted by many early observers. Its importance was emphasized by 

 Sachs ('82), and Kolliker ('85), and later by Minot (Proc. Am. Ass. Adv. Set., '90), who 

 concludes that a relative increase in the quantity of cytoplasm is in general characteristic of 

 advancing age. Schwarz (Conn's Beitr'dge, IV.), who has studied the size-relations carefully 

 in growing root-tips, finds the largest nuclei not in the actively dividing tissue (meristem), 

 but in the slightly older, rapidly growing cells. At a later period the nuclei diminish both 

 in relative size and in stainirig-capacity (i.e. nuclein-content). Zacharias ('94, '95) reaches 

 essentially the same result. 



5. P. 27, 1. 19. In nuclei of the spinning-glands of caterpillars Korschelt (A. m. A., 

 XLVII. 3, '96) is able to see the chromatin-granules clearly in life. Cf. Meves (A. m. A., 

 XLVIII. '96). 



6. P. 40, 1. 30. Heidenhain and Cohn (Morph. Arb., VII. I, '97) figure the double 

 centrosomes in this position in several forms of embryonic epithelia, including the epidermis, 

 the neural and sensory epithelia, the mesenteron, the walls of the mesoblastic somites and 

 those of the Wolffian duct. 



7. P. 43. Arthur Meyer (Bot. Zeit., XI., XII., '96) maintains that the cells of all forms 

 of plant tissues are in organic continuity, and accepts the probability that the bodies of all 

 plants and animals are practically continuous masses of protoplasm. 



358* 



