412 SUMMARY OF CURRENT RESEARCHES RELATING TO 



plants, the inference is that the latter arise from tetraspores. 8. The 

 nuclei of the reproductive cells (spermatia and carpogonia) of the sexual 

 plants possess 24 chromosomes. The sporophytic or fusion nucleus, 

 as a result of fertilization, has 48 chromosomes. The sporophytic nuclei 

 give rise by division to the carpospores, which also possess 48 chromo- 

 somes. The carpospores on germination show 48 chromosomes ; and, 

 since 48 chromosomes appear in the vegetative mitoses of the tetrasporic 

 plants, it is inferred that the tetrasporic plants originate from carpo- 

 spores. 4. The male and female plants are gametophytic, while the 

 tetrasporic plants are sporophytic. The sporophytic generation begins 

 with the formation of the sporophytic or fusion nuclei, extends through 

 the formation of the cystocarp and carpospores, and finally terminates 

 with the formation of tetraspores on the tetrasporic plant. With the 

 formation of the tetraspores, the gametophytic generation commences. 

 5. Thus GoralUna is another clear example of the alternation of a sexual 

 plant (gametophyte) with a tetrasporic plant (sporophyte), the cystocarp 

 existing as an early phase of the sporophytic generation. (The paper 

 has been translated from the original Japanese in Tokyo Bot. Mag.^ 

 ]1»18, 27, 279-85, 8 figs.) A. G. 



Spiral Arrang-ement of the Branches in Some Callithamniese. — 

 L. K. RosENVixriE (Z"^/. Dansli. Videnslcab. SeJskah. Biolog. Meddelelser, 

 1920, 2, 70). The results of a detailed examination of five species of 

 Callithamnieai, CaUithamnlon tetr(«jomi,m, 0. Ci)ryinhosum, 0. roseurn, 

 G. furcell arise, and Seirospora Griffilhsiana -. with a view to explaining 

 the discrepancies between the conclusions of Nageli and Kylin on the 

 subject of spiral branching. This paper shows these discrepancies are 

 due to variation of the ramification. Each of the five species examined 

 is discussed in considerable detail, and the variations of ramification 

 are shown in diagrams. A spiral arrangement occurs in all of them, 

 but with varying frequency and direction. The angle of divergence is 

 less constant than in the higher plants, and varies even in the same 

 shoot. In G. roseurn and S. Grlffitliskma the spiral was sometimes 

 interrupted by a shorter or longer stretch with irregularly arranged 

 branches. Change in the direction of the spiral was found in all the 

 five species, and usually takes place suddenly. The spiral arrangement of 

 the branches never begins at the very base either of the primary shoots or, 

 except very rarely, of the lateral shoots. In G. tetragomtm and C. corym- 

 bosmn the first step in the spiral takes place, with very few exceptions, 

 on the outer side of the shoot : this is due to a factor seated in or 

 emanating from the mother axis. This is cnlled by the author 

 '' ectoblastesis," A correlation between the direction of the spiral and 

 the position of the first branch of the second order on the members of 

 the spiral was found, and is here discussed. This correlation was 

 present from the beginning of the spiral, though with somewhat 

 diminished constancy. It is probably a result of the asymmetry of the 

 young axial segments. A detailed study of the division of the apical 

 cell and the shape and division of the young segments will throw light 

 upon the factors determining the spiral arrangement of the branches, 

 and the position of the first branches of the second order. E. S. G. 



