656 SUMMARY OF CURRENT RESEARCHES RELATING TO 



BOTANY. 



A. GENERAL, including the Anatomy and Physiology 

 of the Phanerogamia. 



a. Anatomy. 

 (1) Cell-Structure and Protoplasm. 



Fibrillar Structure of Protoplasm.* — B. Nemec describes in detail 

 the various circumstances in which a fibrillar structure may be detected 

 in the protoplasm of plants. It occurs most commonly in nuclear and 

 cell-division, usually before the actual division, and disappearing after 

 it is completed. The nucleus may put out fibriform appendages, reach- 

 ing to the parietal utricle. Those connected with the transmission of 

 irritation usually make their appearance as homogeneous slightly stain- 

 able threads, enclosed in a more strongly stainable sheath, and run from 

 one parietal utricle to another. The sheath of these fibrils corresponds 

 to the entire substance of the kinoplasm fibres ; except in the case of 

 Blecltnum boreale, where the fihrils have an isolated course in some of 

 the cells. 



The author litters a caution against drawing too close an analogy 

 between the irritation-conducting fibrils and the nerve-system of animals. 

 That the former are not continuous is not a final argument against their 

 function of transmitting irritation. The demonstration of this con- 

 tinuity is often a matter of extreme difficulty. 



The structure of these fibrils is riot uniform. In some plants — 

 Lonchitis ^albescens, Calla pahtstris — they have, when young, more or 

 less of a reticulate character. A good subject for their study is the 

 adventitious roots of Aspidium decussatnm. The bundles are readily 

 seen in the large plerom-cells ; the fibrils themselves are strongly re- 

 fringent, and appear to form a network here and there. The finest 

 branches of the fibrils are to be seen at the ends of the cells ; and it is 

 here that the granular degradation first takes place. They become 

 changed into granular masses composed of numerous spherical bodies. 

 In the roots the fibrils occur in the growing apex, and connect the per- 

 ceptive zone with the motor cells. 



The author is unable to accept Haberlandt's criticism f as in any 

 way weakening his argument that the fibrils act as transmitters of 

 irritation. 



Centrosomes in the Pollen-mother-cells of Lilium longiflorum.J — 

 S. Yamanouchi confirms Guignard's statement §, in opposition to that of 

 other observers, of the presence of centrosomes or centrosome-like bodies 

 in the cells of the higher plants, the object examined being the pollen- 

 mother-cells of Lilium longifiorum. 



In the resting nuclei no structures of this kind were observed ; they 



* Biol. Centralbl., xxi. (1901) pp. 529-38. t Se« infra, p. 607 



X Beih. z. Bot. Centralbl., x. (1901) pp. 301 4 (1 pi.). 

 § Cf. this Journal, 1899, p. 290. 



