482 • BOTANICAL GAZETTE [june 



the Taxineae, Podocarpineae, and many Cupressineae have two cotyledons, and 

 that each cotyledon (Podocarpineae being excepted) contains one vascular strand 

 and the primary root is diarch. Among the Abietineae, however, in which poly- 

 cotyledony prevails, each cotyledon has a single vascular strand, but the number 

 of poles of the primary root holds no obvious relation to the number of cotyledons. 



In summarizing the evidence of splitting, the authors add the following 

 testimony: the occurrence of partially split cotyledons, the frequent obvious 

 grouping of cotyledons, and the cases of transition. Pinus contorta Murrayana 

 may be selected as an illustration of the last case, in which form three entire 

 cotyledons were found, one of them much larger than the other two and contain- 

 ing two entirely distinct vascular strands. The authors speak of this as a case 

 of one whole cotyledon and two half-cotyledons. Trouble of course comes with 

 the higher numbers of cotyledons, and at this point the explanation offered is not 

 clear. It is acknowledged that in some cases an increased number of cotyledons 

 may result from the appearance of extra primordia, which represent the dis- 

 placement of foliage leaves from the first stem node to the cotyledonary node. 



The general summary of facts contains the following items: the occurrence 

 of more or less complete cotyledonary tubes (over 20 species cited); the existence 

 of cases of incomplete splitting (4 species cited); the general presence of cotyle- 

 donary resin ducts (several in araucarians, two in 12 species cited, one in 6 species, 

 and none in 6 species or more) ; the occurrence of 4-8 vascular strands in each 

 cotyledon of Araucaria, and of one strand in the cotyledons of Tsuga, Abies, 

 Picea, Cedrus, Pinus, and Larix; the occurrence of mesarch structure in occa- 

 sional cotyledons of Tsuga canadensis, Pinus Pinea, and P. Gerardiana. 



Shaw 26 has investigated the seedling of Araucaria Bidtvillii, a tuberous 

 species and one not studied by Hill and Fraine. He finds that the cotyledonary 

 vascular strands are very numerous and variable (12 to 16), that the poles of the 

 root are equally variable (5 to 7), and that there is a very confused connection 

 between the two. The protoxylem groups of the root are gradually reduced until 

 the diarch condition is finally attained.— J. M. C. 



The Piccard rotation experiments.— Haberlandt 2 ? has repeated Piccard's 



rotation experiments, 28 for which he used the seedlings of Vicia Faba, Lupimis 



albus, and Phaseolus multiftorus. He characterizes Piccard's conception as 



good, but the execution of the experiments and the interpretation of the results 

 as faulty. 



He claims to have eliminated all Piccard's technical errors by devising a 

 very substantial and accurate centrifuge, and by securely fastening the seedlings 



26 Shaw, F. J. F., The seedling structure of Araucaria Bidwillii. Annals of 

 Botany 23:321-334. pi. 21. figs. 6. 1909. 



2 7 H \berla.vdt, G., Ueber die Verteilung der geotropischen Sensibilitat in der 

 Wurzel. Jahrb. Wiss. Bot. 45:575-600. 1909. 



23 Piccard, August, Neue Versuche uber die tfeotropische Sensibilitat der Wurzel- 



e. Tahrh \Vr« IW * n . 



spitze. Jahrb. Wiss. Bot. 40:94-102. 1904. 



