ins 



K NOW 1. 1: DC I- 



MMini. I'd 2. 



tin- sCalk ami cap contain a systi-tn of iiiilktiilx-s, aritl a 

 Cdimccd'd svstom of air-cavities is alsn tlevclopcil ~[hr wliolf 

 offering an analogy widi the arranjjfiiicnl nf the tissues in mie 

 of the liiKher plants. The deli(|uescenco of the cap is a kind 

 of self-dijjestion, occin-rinK <|uitc iiulepcndcntly of the action of 

 bacteria and etVecled by a number of ferments which act upon 

 proteins. The liorn-likc substance ehilin occurs not only in 

 the coats of the spores, but also in the outer tissue of the stalk 

 and cap: the yills contain practically no chitin, and it is 

 probably owinj^ to this that the ^'ills deli(|uesce more readily 

 than the other parts of the fruit-body. Any part of stalk or 

 cap is capable of regeneration, new fruit-bodies being formed 

 by this process ; the plant shows definite polarity, there being 

 greater power of regeneration in the side facing the substratum 

 or turned from the light. Numerous grafting experiments 

 were made, the yoimg fruit-body of one species being grafted 

 on the stalk of a different species: fusion took place between 

 the threads of scion and stock, and the form of the mature 

 fruit-body showed evidence of reciprocal action between the two 

 species: the spores, however, were not influenced by grafting. 

 Simil.ir grafting experiments were made with various fungi in 

 addition to Coprinits. and in some cases Weir found 

 evidence of reciprocal parasitism between the two species 

 used. 



Like Buller's work, this paper by Weir is perhaps even more 

 notable as an indication of the interesting lines of research it 

 suggests than for the actual results obtained by the writer, 

 novel and striking as these results are in themselves. 



PHOTOSYNTHESIS IN ALGAE.— It has long been 

 known that the green pigment chlorophyll absorbs chiefly the 

 red and blue rays of light. In plants possessing other pigments 

 in addition to chlorophyll, the absorption spectrum is some- 

 what diflerent. Dangeard {Comptes rendus, 19111 has now 

 proved that even in green plants the infra-red rays are 

 absorbed and utilised in growth, though there is apparently no 

 absorption of the ultra-violet rays. Dangeard has also found 

 that the blue-green algae (Cyanophyceae) are capable of 

 utilising the infra- red rays to a large extent. Meinhold iBcitr. 

 Biol, tier Pfltnizen, 1911) has studied the Diatomaceae from 

 this point of view, and finds that here, as in green plants, there 

 are two maxima of assimilation, one being in the red and the 

 other in the green-blue between lines C and F — not, as in 

 green plants, in the blue between lines F and G. The results 

 of experiments on assimilation, on being compared with those 

 obtained by means of the spectroscope, show that the maxima 

 of absorption and assimilation by no means correspond ; that 

 is to say. some of the rays which the plant absorbs are not 

 utihsed in photosynthesis, though they may be of importance in 

 other processes of life. 



BIOLOGY OF THE HORSETAIL iEOUlSHTCM).— In 

 an interesting paper, Ludwigs {Flora. N.l". Band 3, 191 1 1 gi\es 

 the results of various observations and experiments he has 

 made on the Horsetails (species of Eqiiisetiiiii). He finds 

 that there is a characteristic difference between the leaves on 

 the underground and aeiial stems. The leaves of the rhizome, 

 which persist much longer than those of the aerial stem, bear 

 hairs on both sides; tho»e on the upper side of the leaf serve 

 to protect the delicate tissues of the growing-point, while the 

 hairs on the underside secrete mucilage, making the growing 

 tip of the rhizome slimy, and therefore helping it to push 

 through the soil. On the aerial stem these hairs occur on 

 the upper surface of the leaves, but not on the lower. 

 Ludwigs finds that by suitable culture methods, the rhizome 

 can be made to grow into an aerial shoot, and vice versa : 

 annual shoots may be made perennial; the normally colourless 

 and unbranchcd fertile shoots of the field horsetail may be 

 caused to develop chlorophyll and to produce branches ; male 

 prothalii can be changed into female, and vice versa. 

 Regeneration takes place when pieces of the shoot, or even of 

 the prothallus, are cultivated : in the latter case, new 

 prothalii grow out and may become det.ached. The author 

 states, in opposition to Mower, that the nutrition of the 

 developing spores is not due to the degeneration of some of 

 the spore-mother-cells, but solely to the special nutritive layer 



or t.ipclum. He also ilescribes the manner in which the 

 antheridiiim opens to discharge the male cells; apparently the 

 process resembles that seen in some mosses, there being a 

 special cap or lid-cell which is del.iched, after becoming 

 mucilaginous and swollen. 



THE "CALYX-TUBE '• OF ROSACEAE.— The family 

 Rosaceae shows great variety in the form of the flower, 

 largely due to the varying degree of " perigyny " or '" hemi- 

 epigyny ■' exhibited by the flowers in the different genera. 

 Hillmann iBeih. Bot. Ceiitralblatl. Band 36. Abt, ll has 

 made a careful examination of the so-called " calyx-tube " or 

 "receptacle-tube," for which he prefers the term "hypanth," and 

 from his investigations on the anatomy of this tubular structure 

 he concludes that in this family we have to deal with different 

 kinds of tubular organs, which are not all formed in the same 

 way. In the Rose, the tube is purely an axial structure, a 

 hollow prolongation of the receptacle or top of the flower- 

 stalk. In the Apple sub-family (Pomoideae). the "receptacle- 

 tube " consists of both axis and calyx. In most of the remain- 

 ing members of the family, however, the hypanth is the 

 product of fused leaves. Hillmann believes that this is clearly 

 shown by the structure of the flower in Avens, where the 

 flower axis is prolonged above the cup-like outgrowth, and the 

 latter can hardly be explained otherwise than as the product 

 of congenital fusion of leaves. 



EVOLUTION OF ALGAE. — In recent speculations on 

 the evolution of plants, it has generally been assumed that the 

 earliest vegetable organisms possessed chlorophyll and 

 belonged to the green algae iChlorophyceael. That these 

 arose from green flagellates, while the brown and red algae 

 arose probably from brown and red flagellates, appears to be 

 supported by the discovery of transitional forms in each of 

 the three series, green, brown, and red. Most writers on the 

 subject, however, have assumed that whatever the course of 

 evolution may have been, the green algae came first. This 

 assumption has recently been combated by Brunnthaler 

 tBiol. Ceiifralblaff, 19111. who argues that in order to 

 arrive ^t correct views regarding the phylogeny of the algae, it 

 is necessary to take into account the probable conditions of 

 life in the earlier periods of geological history. He rejects the 

 view that there is any direct relationship between algae and 

 flagellates, and regards the living forms of the latter as the 

 termination of an ancient series of organisms, of which the 

 earliest members may, however, have given rise to the red 

 algae. 



According to Brunnthaler, the most ancient algae are the 

 red forms, or Rhodophyceae, and he bases this view upon the 

 following arguments. The earliest plants must have been 

 marine free- swimming forms: the absence of free-swimming 

 forms among the present-day red algae indicates the great 

 age of the group. Again, the red colour is an adaptation to 

 life in the deep sea and in the dim light of the primitive world 

 with its dense cloud canopy, for the red pigment enables the 

 plant to absorb the green rays in which that light is rich. 

 The ancient lineage of the group is further shown by the 

 absence at the present day of primitive types in the red algae, 

 and by the absence of motile reproductive cells as well as of 

 free-swimming species. 



The brown algae 1 Phaeophyceael came next, according to this 

 view, arising partly from brown flagellates and partly from red 

 algae. That this is a younger group is indicated by the extra- 

 ordinarily diverse structure of the reproductive organs, the 

 constant presence of swimming reproductive cells, and the 

 adaptation of the brown pigment to absorb r.aysfrom light more 

 closely approaching that of the present world, but still with an 

 atmosphere richer in water-vapour than that of to-day. In 

 the meantime, the primeval red algae had become adapted to 

 the dim ancient light, and therefore became restricted to the 

 depths of the sea, leaving the upper waters as an open field 

 for the evolution of the brown seaweed population w^hen the 

 latter appeared. 



The green Alg.ae (Chlorophyceae) are the yomigest group 

 of algae to appear in the succession. Their green colour is an 

 adaptation to the clear light of later times, and they evolved in 



