September 11, 1885.] 



SCIENCE 



225 



them. All the observed facts of the conjugation of 

 these algae tend to prove that sexuality is in its 

 beginning, but as yet there is no differentiation into 

 male and female elements; so that we cannot speak 

 of a bisexuality, although there is a union of two dis- 

 tinct bodies of protoplasm. One fact not observed 

 by Bennett is that of the formation of a resting spore 

 by union of the protoplasm of two adjacent cells of 

 the same filament. The position of the Zygnemaceae 

 is among the lower Thallophytes, but little above the 

 Protophytes. 



' On the process of cross-fertilization in Cam- 

 panula americana ' was the title of a paper pre- 

 sented by Prof. C. R. Barnes. In this strongly pro- 

 terandrous species, the pollen is scraped out of the 

 anthers, by the hairy style, at a period anterior to 

 the maturation of the stigmas; before the occurrence 

 of which, the pollen has disappeared from the style. 

 In this manner cross-fertilization is rendered certain. 

 The pollen develops normally. The stigmas are 

 held together until mature by interlocking papillae. 

 The hairs on the style become introverted, and thus 

 free the pollen. The pollen-spore contains two 

 nuclei, the larger of which (the vegetative) becomes 

 disorganized shortly after entering the pollen-tube, 

 the smaller (the spindle-shaped), generative nucleus 

 persists. The embryo sac is cylindrical with a 

 gradual enlargement near the upper end, where is 

 located the egg apparatus, and an abrupt enlarge- 

 ment at the base in which lie the antipodal cells. 

 The pollen-tubes enter the style between the bases of 

 the papillae of the stigma, pass down in the strands 

 of the conducting tissue, and not through the cen- 

 tral canal around which the tissue is arranged. 



Dr. C. Y. Riley presented a paper on the song- 

 notes of the periodical cicada, and the mechanism by 

 which they are produced. The author gave the first 

 accurate description of the three characteristic notes 

 of the insect, noting the variations for the individual 

 and for thermal and hygrometric conditions of the 

 atmosphere. The same author, in another paper, cor- 

 rected the erroneous notions, that var. Cassinii Fish 

 represents the race tredecim Riley, and that the twigs 

 containing the eggs necessarily break off before the 

 hatching of the larvae. 



In a paper on the proof that bacteria are the direct 

 cause of the disease known as pear blight, Mr. J. 

 C. Arthur demonstrated by the results of his care- 

 fully conducted experiments that, 1°. Sap from an 

 infested tree when inoculated into a healthy tree in- 

 variably produced the disease called blight. 2°. When 

 cultures to the sixth generation of organisms were 

 made with all precaution to prevent error, and healthy 

 trees were inoculated with the pure culture of this 

 sixth generation, the tree is stricken with blight, 

 starting from the point of inoculation, and gradually 

 extending over the whole plant. 3°. That wherever 

 there is a blight not produced by freezing, bacteria 

 of this species are invariably present. In order to 

 complete the value of this work, there yet remains to 

 discover some certain method of prevention or cure. 



A paper on aquatic respiration in soft-shelled turtles 

 <Asi)idonectes and Amyda) was presented by Profs. 



Simon H. and S. S. Phelps Gage as a contribution 

 to the physiology of respiration in vertebrates. One 

 of the characteristics by which reptiles are said to be 

 distinguished from amphibians is, that their respira- 

 tion is exclusively aerial at all periods of their life. 

 This assertion is made by all authors, except Agassiz, 

 who adds a slight qualification. On the strength of 

 the experiments and observations of the authors, this 

 general character must be given up, since they have 

 demonstrated beyond a doubt that at least in the soft- 

 shelled turtles respiration is normally and constantly 

 carried on by means of a respiratory apparatus, whose 

 essential features, physiologically considered, are 

 those of a gill. There is here, as in the adult Dipnoi, 

 and some ganoids, a double respiration, aerial and 

 aquatic. The facts which go to prove that we have 

 in this case to deal with aquatic respiration are, 1°. 

 Rhythmical movements of the hyoid apparatus, by 

 means of which water is forced in and out of the 

 pharyngeal cavity, thus insuring a constant flow of 

 water over the pharyngeal mucosa. 2°. The habit 

 these turtles have of remaining under water from 

 two to ten hours voluntarily, and their ability to 

 endure a submersion of fifteen hours in running 

 water without apparent inconvenience. 3°. The 

 structure of the lining membrane of the pharynx 

 with the copious blood-supply. The surface of the 

 mucosa is prolonged into simple and compound papil- 

 lae of various shapes and sizes, many of them recall- 

 ing the gill tufts of Necturus. The fourth and abso- 

 lute proof of the aquatic respiration consists in the 

 results of chemical analyses made by Professors Rich 

 and Holton of Cornell university, who carefully tested 

 the water in which a turtle had been immersed with- 

 out access to air, and found a marked decrease in the 

 amount of free oxygen in the water, and an increase 

 in the quantity of carbon dioxide held in solution. 



The following table shows the result of the analyses. 

 In the first column is given the amount of oxygen in 

 the quantity of water used in the experiment (1 kg). 

 The second column contains the quantity of CO^ 

 which could be made from this O. The third column 

 contains the actual amount of the CO 9 found in the 

 water, the excess of which over the amount to be 

 from the oxygen in water itself is given in the fourth 

 column. 



O. CO2. Actual CO.. Excess Coo. 



July 11, 71 mg. 97|mg. 231 mg. 133fmg. 

 Aug, 8, 32 " 44 " 212-/0 " 168.7 " 

 Aug. 9, 39 '' 55f " 168.7 '' II8-/0 '•' 



The excess of CO 2 in the water is accounted for 

 by the presence of a certain quantity of O in the 

 lungs of the animal at the moment of submersion, 

 and by the intramolecular O of the tissues of the 

 animal's body. An analysis of the contents of the 

 lung revealed the total absence of O, and of CO.., was 

 found only a trace. The O is taken from the water 

 by the papillate pharyngeal mucosa, the details of the 

 structure of which lack of space forbids giving here. 



Prof. C. E. Bessey read a paper on the inflorescence 

 of Cuscuta glomerata. In his studies of this degraded 

 morning-glory, the author has discovered that the 

 dodder produces its flowers upon short, adventitious 



