438 SUMMARY OF CURRENT RESEARCHES RELATING TO 



does not think that it is altogether the absence of iron that causes the 

 disease, as plants growing on the same soil are attacked irregularly, some 

 escaping altogether. PI is experience leads him to think that the roots or 

 conducting vessels suffer some alteration which prevents the minute 

 quantities of iron contained in the sap from reaching the leaves. A too 

 rapid and luxuriant growth favours the disease. The following experiment 

 has, he considers, an important bearing on vegetable physiology. Certain 

 acacia trees showed symptoms of chlorosis, in particular the thick branches 

 of a twenty-year old tree. The author caused holes to be bored in the 

 main stem, just beneath the bifurcation of the branch with the core of the 

 tree. In these holes he placed corks fitted with funnels, charged afterwards 

 with ferrous sulphate or ferric chloride in solution. In dry weather the 

 tree absorbed the solutions readily, the leaves in the line of each funnel 

 becoming quite green in 10 to 14 days, while those not in the line re- 

 mained white. This the author thinks a proof that each branch and twig 

 has its own sap-ducts. 



Freezing of Tissues.* — Herr H. Miiller-Thurgau gives the details of a 

 large number of experiments connected with the freezing of tissues, especially 

 on potatoes and on leaves. lie regards the cause of the death of the 

 protoplasm to be not so much the low temperature or the desiccation, or the 

 processes connected with thawing, as the actual freezing itself. 



Plants poisonous to Fish.j — Dr. L. Eadlkofer gives a list of upwards 

 of 150 species of flowering plants which are more or less poisonous to 

 fish, many of which are used for purposes of fishing. 



B. CRYPTOGAMIA. 



Cryptogamia Vascularia. 



Gemmiparons roots of Anisogonium.| — M. P. Lachmann observed in 

 Anisogonium [section of Asple7ilum^ certain roots, the radicular nature of 

 which was fully determined, and which gave rise to a bud at their apices. 

 On the exterior the passage of the root to the bud is marked by a very 

 apparent swelling ; on the interior a transition of radicular to cauline 

 structure is noticed. These buds develop and give rise to stems with 

 ordinary fronds. 



Muscinese. 



Anatomy and Physiology of Mosses.§— Dr. G. Haberlandt enters, in 

 great detail, into the structure of the vegetative organs of Mosses. The 

 following is a summary, of the more important conclusions arrived at, the 

 author regarding the histological differentiation of Musci as much more 

 advanced than is generally assumed. 



(1) The epidermal system is represented by an epidermis which is 

 usually typically developed on the sporogonium, and is sometimes covered 

 by a coating of wax. On it are sometimes developed trichomic structures, 

 as on the calyptra of Polytrichum. The tuberous stem of Buxhaumia apJiylla 

 has a suberous epidermis. 



(2) The mechanical system consists of steroids, characterized not only 



* Laiidwirths. Jalirb., xv. (1S8G) j'p. 453-609 (4 pis.). See Bot. Centralbl., xxix. 

 (1887) p. 76. 



t SB. K. B. Akad. Wiss Miinrlicn, xvi. (1886) pp. 379-416. 



X Bull. Soc. Bot. Lyon, May 25, 1886. See Bull. Soc. Bot France, viii. (1886), Rev. 

 Blbl., p. 227. 



§ Prin-:;.sh(im's Jalirb. f. Wiss. Bot., xvii. (1886) pp. 359-49S (7 pis.). 



