47 



that^in plants grown in moist places, therefore in weakly 

 transpiring individuals, the whole length of the vascular 

 bundles is less than in those transpiring strongly. It 

 will douttless he possible to demonstrate the same hypopl- 

 asia also in a comparison of the &an and shade leaves of 

 our deciduous trees , etQ. 



In the weakly grovm specimens, which Daniel 

 grev; from the seeds of and Alliaria, grafted on 

 a turnip-rooted cabbage, (Brassica .lilapobrassica) 

 nothing but arrested development occurs* One will 

 not dare, from the appearance of scanty tissue dif- 

 ferentiation, to conclude upon a "creation des var- 

 ieties nouvelles au moyen de la greffe/'^^, as 

 Daniel attempts to do, ' ' 



The study of the anatomy of blossoms and fru it and con- 

 sideration of the second ary_t issues^ can furnish further 

 material for our consideration. Also the differentiation 

 of anthers and anther partitions ,.•' as well as ovml.e and the 

 different iation of the fruit and -seed receptacles is sub- 

 ject to the action of the same arresting factors, of which 

 (49) Election has so often been made,^ In cambial products, ar- 

 restment in tissue-differentiation is shovra by the fact that 

 the difference in xylem in autumn and spring wood disappears, 

 or, at least, degenerates strongly s 



1. C. H. Acad. Sc. Paris, 1894, T, CXVIII , p, 992, 



j,S, Wieler, fUeb, Bezieh, zw, d. sek» Dickenwachst. u,d. 

 Ernahrungsverhaltn. d, Baume. Thar. Forstl. Jahrb,, 189E,Bd# 

 XLII, p. 7 2) saw that the formation of the annual rings could 

 be lacking. jSzij (Eine Abnormitat in d. Abgrenzung ds Jahres- 

 riiige. Sitzungsber. Naturf. Fr, Berlin, 1890, p. 138) ob- 

 served thin walled autumn wood; further statements also in 

 Verh. Bot. Ver. Prov. Brandenbujrg , 187 9 (Ueb, d, Verdoppel- 

 ung d. Jahresringe) . On the anatomy of the stamens and ovules 

 one should compare, for example, Guignard, S. 1. organes 

 reproducteurs des hybrides vegetaux, C. R. Acad, Sc, Paris, 

 1886, T. GUI, p. 769. Amelung, Ueb. Etiolement. Flora, 

 1894, Bd, LXXVIII p. E04, on the normal arrested,, develop- 

 ments. Compare also Pamiller, Biogenet, Unters, ub. Verkum- 

 merte od. umgebildete Sexualorgane, Flora, 1896, Bd. LXXXII , 

 p. 133, The stamens of the cleistogamic blossoms in places 

 do not develop any fibro-cells (Lecler Du Sablon, Rech. s. 1. 

 fleurs cleistogames. Rev. gen. de Bot., 1900 T. XII, p, 305. 

 Rossler, Beitr. z. Kleistogaraie , Flora, 1900, Bd. LXXXVII, 

 p. 479) . 



The same arrestment in differentiation might be 

 brought about also by exposure to weak light or the action 

 of damp air. On arrested developments of Ovula compare also 

 Miller- Thurgau, 2, Jahresber. Versuchsstat. Wadensweil, and 

 still others, on arrested developments of the fruit and 

 seed pods, compare for example, Amelung, (loc. cit.) who 

 harvested deformed Cucurbita seed on cultures in the dark. 

 It is well known that finiits attacked by Exoascus Pruni 

 form no hard pit. 



