ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 371 



Structure and Development. 

 Veg-etative. 



Anatomy and Morphology of Roots of Conifers.* — W. Nbelle 

 publishes the results of his investigations upon the anatomy and 

 morphology of the roots of the Coniferge. The present paper deals 

 with the primary and secondary cortex and centra] cylinder of various 

 species representing the important genera, while two sections are devoted 

 bo mycorhiza and heterorhizy. 



The chief results are embodied in a comprehensive table of classifica- 

 tion in which the author divides the Coniferae into two main groups. 

 In the first group bands of thickening are absent in the primary cortex 

 and there is no hypodermis, but endotrichia (i.e. root-hairs formed from 

 cells lying in the second and third row below the surface) may develop. 

 In the secondary cortex suberized crystal-cells and sclerenchyma are 

 found ; layers of cork form the outer surface. Subdivision is based 

 upon the character of the roots, position and formation of resin-canals, 

 and upon the crystal-cells and tannin-sacs. This group includes all the 

 Abietineae. 



In the second group there are bands of thickening in all except the 

 outermost layers of the primary cortex. Both root-hairs and resin- 

 canals are absent. Subdivision is based upon the character of the 

 thickened bands, the presence or absence of hypodermis and primary 

 resin-canals, etc. This group includes the Araueariaceaj, Taxodieas, and 

 Cupressinffi. 



In conclusion, the author describes three kinds of roots (heterorhizia ) 

 and points out that mycorhiza are found in connexion with the roots 

 of all the Coniferae, but that only in the Abietinea? are they typically 

 ectotropic : in the Araucariacea?, Taxodieae and Cupressinea? the myce- 

 lium is endotropic. The presence of an ectotropic mycelium appears to 

 influence not only the structure of the cortex but also that of the 

 central cylinder. 



Origin and Development of Bulbs in the Genus Erytkonium. — 

 31. Blodgett draws the following conclusions from his study. The de- 

 layed development of the embryo is associated with a large store of 

 endosperm, which is drawn upon by the germinating embryo during the 

 season when vegetative activity is low ; the young seedling is established 

 in the soil early in the spring, the endosperm furnishing the needed 

 materials for its development. With the exhaustion of the reserve 

 material of the seed, the primary root is developed, and the cotyledon 

 is elevated into the air and light ; the cotyledon is the only leaf exposed 

 to the light by the seedling. The stem apex, located in a narrow cavity 

 in the base of the cotyledon, is carried forward by the elongation of the 

 embryo, and after elevation of the cotyledon, is carried farther into the 

 soil by the elongation of the walls of the cavity. The short period of 

 vegetative activity, and the prompt descent of the stem apex in the 

 dropper, would indicate adjustment to short growing seasons ; the brevity 

 -of the active season is a feature of the life-cycle. The tendency on the 



* Bot. Zeit. lxviii. (1910) pp. 169-266 (50 figs.). 



t Bot. Gaz., 1. (1910) pp. 340-73 (3 pis. and figs, in text). 



