50 



SCIENCE. 



I Vol.. I., No. 2. 



Gilbert notes also that this plant is also dispersed 

 through the agency of the larvsB of cartdisflies (a 

 common bait used by anglers). The larvas have an 

 envelope composed of minute shells, bits of dead 

 wood, fragments of plants, etc.; and sometimes this 

 artificial carapace is furnished with five or six bulb- 

 lets of Utricularia. These are borne about by the 

 larvas until at an early stage of growth they become 

 detached from them, and then they take root in the 

 earth at once. — {Bull. soc. roy. bot. Beltj., Dec. 28, 

 1882.) G. L. G. ' [134 



Fertilization of Gerardia pedicularia. — Pro- 

 fessor Bailey, who has already published several ob- 

 servations on the perforation of the flowers of this 

 species by predatory humble-bees, has found that 

 when few of these insects visit the flowers they are 

 not so apt to perforate them. He concludes, with 

 Fr. Darwin, that they only puncture flowers whose 

 nectar they can reach normally, when competition 

 forces them to work very rapidly. — (Amer! nat, 

 Dec, 1882.) w. T. [135 



Spring floras. — The influence of temperature 

 has been applied by Dr. Taylor to the explanation of 

 vernal floras. Species that bloom early are frequent- 

 ly identical with, or closely related to, alpine species 

 of the same latitude; and these, as is well known, 

 bear a similar relation to arctic species. Alpine and 

 arctic floras are commonly explained as remnants of 

 the post-glacial flora, which have survived in conse- 

 quence of the protection afforded by the cold of high 

 altitudes or latitudes. Spring flowers are claimed to 

 receive similar protection by their time of flowering. 

 It is a suggestive fact, that when our early-flowering 

 species also occur at high elevations, or farther north, 

 theybloommuch later than with us. — ( iVato-e, N"o v. 

 2; Science ijossix>, Dec, 1882; Bot. rjaz., Dec, 1882.) 

 w. T. [136 



Fall blooming of Menyanthes trifoliata. — 

 This plant was found blooming abundantly in Rhode 

 Island on the 23d of October, by Prof. W. W. Bailey. 

 The swamp in which it grew had been desiccated by 

 a long summer drought, which seems to have had 

 upon it the effect of its normal winter rest, so that 

 the following autumn i-ains and continued warm 

 weather induced a season of general and vigorous 

 bloom. — (C'ouH. 6oi. ya«., Dec, 1882. ) s. w. [137 

 {Systematic and geji^ral.) 



Jamaica ferns. — A critical examination of the 

 Jamaica ferns in the herbaria of the British museum 

 and Kew, by G. S. Jenman, results in the addition 

 of eight new species, with some not before credited 

 to the island, and corrections in previous determina- 

 tions. — (J^ourn. bot., Nov., 1882.) s. "vv. [138 



New American composite. — -E. L. Greene re- 

 describes from fuller material his proposed new genus, 

 Holozonia, intermediate between Lagophylla and 

 Hemizonia, of a single species (11. filipes), found in 

 mountain streamlets east of Napa Valley, California. 

 — {Ton: bot. bull., Dec, 1SS2.) s. w. [139 



Forest-trees of the gulf region.— A similar but 

 more detailed account of the more important forest- 

 trees in the States bordering the Gulf of Mexico, by 

 Dr. Charles Mohr. —(Z6ici.) s. w. [140 



Origin of Cassia lignea. — The cassia districts 

 of southern China have been recently visited by Mr. 

 Ford; and the tree which is found to be cultivated 

 there for the supply of Chinese cinn.amon, or the 

 cassia-bark of commerce. Professor Dyer of Kew 

 identifies with the Cinnamomum cassia of Blume. 

 An account of its cultivation, the preparation of the 

 bark, etc, is given. — {Journ. Linn. .soc. Lund., 

 Dec, 1882.) s. w. , [141 



ZOOLOGY. 



Coelenterates. 



Nature of the green cells of Hydra. — The (|ues- 

 tion whether any animals are able to produce clilo- 

 rophyl is now attracting considerable attention; and 

 as Geddes and others have stated that such animals 

 as Hydra and Spongilla do have the power to vege- 

 tate their own intrinsic chlorophyl. Dr. Otto Hamann 

 has made a careful examination of the manner in 

 which the green cells make their appearance in the 

 egg of Hydra. From the study of sections through 

 the ovarian ovum at successive stages of develop- 

 ment, he concludes that the green bodies are not 

 developed in the egg, but that they make their ap- 

 pearance suddenly, and are full-grown as soon as 

 they are found at all ; that they migrate into the 

 ovum, through the supporting layer from the endo- 

 derm. He thinks that the bodies which Kleinen- 

 berg described in the egg, as the early stages of the 

 green cells, are in reality early stages in the develop- 

 ment of the pseudo-cells. 



Besides examining sections, he has removed the 

 green cells from the body of the hydra, and has cul- 

 tivated them in water; and he finds that when thus 

 treated they thrive and multiply, and are apparently 

 under conditions of life which are as natural as those 

 to which they are exposed in the cells of the animal. 

 They multiply rapidly in both cases by repeated 

 division into fours. He states, on the authority of 

 Dr. Dalmer, that the green bodies of Spongilla and 

 Paramarcium also multiply by division into fours, 

 and that they will thrive and multiply, like those 

 of Hydra, in water. From these reasons, as well as 

 from the fact that they are not formed by the egg of 

 Hydra, but migrate into it, and from the fact that 

 they have a cell-wall and nucleus, he concludes that 

 they are algae; and he therefore accepts Brandt's 

 conclusion, that, in every case where chloi-ophyl is 

 present in animals, we have to do with unicellular 

 algae, which are both morphologically and physiologi- 

 cally independent. 



Brandt's statement that a green Hydra, when 

 placed among specimens of the brown Hydra, inocit- 

 lates them with its alga, and thus converts them into 

 its own species, he disputes, on the ground that his 

 own experiments in this dii'ection failed, and also for 

 the reason that the two forms are distinguished by 

 many specific characteristics which have nothing to 

 do with the presence or absence of the green bodies. 

 He also doubts the propriety of giving specific names 

 to these algae at present. 



As regards the relation between the alga and its 

 host, he believes that the Hydra derives no particular 

 benefit from the oxygen given off by the algae, al- 

 though it may digest them. He does not regard the 

 alga as in any way dependent upon the Hydra. — 

 {Zeltschr. wiss. zool., xxxvii. 457.) 



A directly opposite view regarding the nature of the 

 green bodies of Hydra is advocated by William Mar- 

 shall, who concludes, from the fact that they remained 

 without change in a Hydi-a which was kept in the 

 dark for six weeks, that they are not algae but are 

 characteristic of the animal itself. He regards the 

 green color of Hydra viridis as a protective resem- 

 blance to the fresh green plants among which it lives. 

 — (Ibid, em.) w. K. B. [142 



Interesting observations on Hydra viridis. — 

 The paper last noticed contains a number of facts 

 regarding this species, which, although they are not 

 strictly new, have never received due attention. Mar- 

 shall has verified Baker's observation, made 140 years 

 ago, that, when a parent Hydra is injured, one of the 



