and Laboratory Methods. 1503 



and in the cork cambium, the threads are chiefly on the radial walls. This sug- 

 gests that in conifers food supplies and stimuli are conducted mostly in a tangen- 

 tial and vertical direction. c. j. c. 



Arnold!, W. Beitrage zur Morphologic einiger In Gymnosperms, aS a rule, only one 

 Gymnospermen. I. Die Entwickelung des , ^^ . • i i i 



Kndosperms bei Sequoia sempervirens. embryo sac attains any considerable 

 Bull, des Natur.de Moscou, Pp. 1-13, pis. development. Very rarely two embryo 

 ' ^' sacs develop in Taxiis, and in one 



instance, two embryo sacs have been seen in Pinus sylvestris. In Sequoia, how- 

 ever, several embryo sacs begin to develop, and in Gnetiim it is the rule for 

 several sacs to develop almost to maturity before one of them secures any decided 

 advantage. Prof. Arnoldi has taken up the somewhat incomplete work of Shaw, 

 and has made a careful study of the development of the endosperm of Sequoia 

 sempervirens. Free nuclear division takes place in the usual manner in an evenly 

 distributed peripheral layer of protoplasm, but very soon there is a denser 

 accumulation of protoplasm at the lower end of the sac. When the formation of 

 walls begins, three regions of the endosperm may be distinguished : the upper, 

 the lower, and the middle. The upper, and particularly the lower, develop 

 faster than the middle, so that the ends of the sac become filled with a solid 

 tissue, while the nuclei are still almost free in the middle portion. Each nucleus 

 of the middle portion now becomes surrounded by a wall which is open on the 

 inner side ; the walls grow inward, and when the center is reached walls are 

 formed at the inner ends of the cells. The nucleus now begins to divide, and 

 each of these cells (" alveoli ") becomes divided into several cells. Archegonia 

 are formed only from these alveolar cells of the middle region. At the time of 

 fertilization, the upper and lower portions of the endosperm consist of small- 

 celled tissue, while the middle portion is alveolar. Sequoia is regarded as a 

 connecting link between Gnetum and the Angiosperms on the one hand, and 

 between Gymnosperms and the Archegoniates on the other. c. j. c. 



Arnold!, W. Beitrage zur Morphologie und The number of archegonia in Sequoia 



Entwickelungsgeschichte einiger Gymno- . , r 1 • • t 



spermen. II. Ueber die Corpuscula und IS very large, SOme of the writer s draw- 



Pollenschlauche bei Sequoia sempervirens. ings showing as many aS sixty. They 

 Bull, des Natur. de Moscou, Pp. 1-8, pis. ^. • 1 i r 



lo-ii i8qq. sometimes occur singly, but are often 



grouped. In development they resem- 

 ble the archegonia of the Cupressineae, since they are often in direct contact 

 with each other, and do not form any ventral canal cell. There are no proteid 

 vacuoles. The neck consists of two cells, in this respect resembling the older 

 Gymnosperms. The pollen tube grows through the nucellus, not between the 

 nucellus and integument, as described by Shaw. At the time of fertilization the 

 pollen tube contains the two male cells of equal size, and two small nuclei, one 

 of which is the tube nucleus and the other " the nucleus of the cell which united 

 the generative cell with the microspore wall." The general structure of the 

 pollen tube and its contents agrees with the Cupressineae. The morphological 

 considerations, together with the geographical distribution, lead to the conclusion 

 that Sequoia is nearly related to the ancient type from which the modem Arau- 

 carias and Cupressineae have descended. c. j. c. 



