Dec, 1907.] Compensatory Growth in Podarke obscura. 217 



Fig. 9. — -April 28, 1906. Two celled embryo sac with three megas- 

 pores above. B. & L. ^ in.-^ in. 



Fig. 10. — April 28, 1906. Shows conjugating polar nuclei, three anti' 

 podals and egg apparatus. B. & L. ^ in.-| in. 



Fig. 11. — May 19, 1906. Mature embryo sac showing conjugating 

 polar nuclei, the egg and antipodals. B. & L. ^ in.-^ in. 



Fig. 12. — May 19, 1906. Embryo sac with two endosperm cells, sep- 

 arated by a wall, also the vanishing antipodals, oospore and synergids. 

 B. & L. i in.-i in. 



Fig. 13. — May 19, 1906. Embryo sac showing three endosperm walls, 

 three vanishing antipodals and complete egg apparatus. B. & I^. h in.-| in 



Fig. 14. — May 19, 1906. Showing oospore with one endosperm nucleus 

 and remnants of pollen tube. B. &. L. J in.-^ in. 



Fig. 15. — May 26, 1906. Embryo sac without definite endosperm walls 

 and with dissolving antipodals. (The delicate walls have probably been 

 destroyed by the technique.) B. & L. ^ in.-^ in. 



Fig. 16. — May 19, 1906. Embryo sac showing thirteen endosperm 

 cells, the lowest one divided by a vertical wall. The egg is still in the one 

 celled stage and the antipodals are still distinct. B. & L. ^ in.-^ in. 



Fig. 17. — June 10, 1906. Showing young embryo surrounded by en- 

 dosperm tissue. The remnants of the pollen tube are visible. B. & L. 

 ^ in.-i in. 



Fig. 18. — September 30, 1905. Section of sporophyll showing mic- 

 rosporocytes, of which two are somewhat larger than the others. B. & 

 L. 1 in.-|^ in. 



Fig. 19. — Jan. 6. 1906. Same as Fig. 18, except that there is a very 

 slight enlargement of the two microsporocytes. B. & L. 1 in.-^ in. 



Fjg. 20. — March 10, 1906. Showing two microsporocytes developed 

 and others undeveloped. B & L. 1 in.-^ in. 



Fig. 21. — April 14, 1906. Microsporocytes with a bridge of sterile 

 tissue between them. Note the dividing nuclei of the sterile tissue, also 

 of the tapetal layer. B. & L. 1 in.-|^ in. 



Fig. 22. — April 21, 1906. Spore tetrads. On the one side only two 

 are visible. The sterile tissue surrounding the tetrads is dissolving. 

 B. & L. 1 in.-i in. 



Fig. 23. — April 28, 1906. Spore tetrad. The sterile tiFsue and tape- 

 tal layer have completely dissolved. B. &: L. ^ in.-^ in. 



Fig. 24. — Mav 5, 1906. Pollen grains with generative and tube nuclei. 

 B. & L. i in.-i in. 



COMPENSATORY GROWTH IN PODARKE OBSCURA.* 



Sergius Morgulis, A. M. 



The idea that vv^hen a lost part is being regenerated by an 

 animal, the whole organism of the latter, and not merely the 

 amputated surface is actively engaged in this process of restora- 

 tion was kept in disrepute. The main objection advanced by 

 the opponents of this idea was that it is at the cut surface only 

 where the histological process of regeneration is to be observed 

 in the appearance of mitotically or amitotically dividing cehs. 

 The writer, however, was forced to the opposite view through 

 some studies of the rate of regeneration, but could not produce 

 sufficient evidence in favor of his view from those studies. Since 



* This and the following note were read before the Ohio Academy of Science at its 

 Seventeenth Annual Meeting in Oxford, Ohio. 



