ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 621 



in 1905-6. He describes and figures A. nigricans, A. Mazei, A. asarifolia 

 (a new species distinct from A. lev is Howe), also a unique plant allied 

 to A. levis but not named specifically, and some plants referred to 

 A. comosa. He also discusses Howe's genus Gladocephalus, and describes 

 a large zonate plant which he considers to be synonymous with Flabdlaria 

 luteqfusca Crouan, and names it G. luteofusca. 



Anatomy and Histology of Macrocystis and Laminaria.* — M. (i. 

 Sykes gives an account of the anatomy and histology of Macrocystis 

 pyrifera and Laminaria saccharina, based upon material specially pre- 

 served, and undertaken in order to determine certain points about which 

 contradictory statements had been published. The conclusions reached by 

 the author are that the " trumpet hyplwe " in both plants are true sieve- 

 tubes, and represent the modified original central cells of the thallus, 

 and may be termed " primary pith filaments." They are homologous 

 with the secondary sieve-tubes of Macrocystis and Laminaria, which are 

 similarly derived from the modified primary cortex of the young thallus. 

 The histology of the sieve-plates in the primary pith filaments and 

 secondary sieve-tubes is essentially the same. Threads are found 

 traversing the young sieve-plate, and each gives rise in the older plates, 

 apparently by means of ferment action, to a slime string inclosed in a 

 rod of callus. The older sieve-plates are obliterated by the deposition 

 of callus in large masses over their surface. Callus is a hvdrated form 

 of cellulose ; it is produced in the young sieve-plates by the action of a 

 ferment on the already formed cell-wall, but afterwards is deposited by 

 the protoplasm on the sieve-plate and on the lateral walls throughout 

 the length of the tube. The histology of these sieve-tubes is shown to 

 agree much with that of the sieve-tubes of Phanerogams. At the advent 

 of the callus the threads acquire an increased capacity for staining ; the 

 development of the sieve-plate is possibly, as in Pinus, a function of 

 ferment action. The slime strings are buried under the thick over- 

 lying callus, and cannot, as in Pinus, be traced through the callus-pad. 

 In young stages of Laminaria saccharina the cells of the hyphas become 

 secondarily attached to those of the primary cortex, probably also in 

 Macrocystis. Protoplasmic threads have been demonstrated throughout 

 the tissues of M. pyrifera and Laminaria saccharina, but in case of 

 secondary attachments their formation is uncertain. 



New Zealand Species of Rhodophyllis.t — A. D. Cotton gives an 

 account of the Xew Zealand species of Rhodophyllis, having made a 

 study of the specimens preserved at Kew, in the British Museum, and in 

 the private possession of R. M. Laing at Christchurch, N.Z. As a result 

 he is able to revise the descriptions of the older species and to describe 

 one novelty. Thus the valid species are Rhodophyllis acanthocarpa, 

 R. Lainyii sp. n., R. membranacea, R. Gunnii, R. lacerata. He lays 

 emphasis on the arrangement of the cortical cells, and shows that the 

 size of the tetrasporangium varies considerably. He has cleared away 

 the difficulty that existed of recognising the plants from their descrip- 

 tions, and of reconciling the statements of different writers. Particularly 



* Ann. of Bot., xxii. (1908) pp. 291-325 (3 pis.). 

 t Kew Bulletin, 1908, pp. 97-102. 



