July 25, 1890.] 



SCIENCE. 



51 



habit, as well as the principle, that all discussion must be con- 

 ducted fairly and kindly, and in a proper spirit, whoever may be 

 on either side the controversy. Make all members of the pro- 

 fession welcome at headquarters ; and let them see that they can- 

 not, without injury to their own interests, defer becoming mem- 

 bers of so representative and powerful a body of their comrades. 

 We think the observing of these few simple principles will insure 

 prosperity, without changes of constitution. 



HEALTH MATTERS. 



Chemical Salts developed in Living Organisms. 

 ■ A MEMOIR by Mr. Robert Irvine and Dr. Sims Woodhead, en- 

 titled "Secretion of Carbonate of Lime by Animals," recently 

 published in the "Proceedings of the Royal Society of Edin- 

 burgh," deals with the interesting question of the assimilation of 

 food and the development of structures partially composed of a 

 definite proportion of insoluble chemical salts. Thus, hens sup- 

 plied with suli)hate of lime, but no other lime salt, produce well- 

 formed egg-shells composed of carbonate of lime. The process of 

 shell-formation in the crab appears to differ chemically from egg- 

 shell development in the hen. Sulphate of lime is not assimilated 

 in the same manner, so that crabs which throw off their shells in 

 artificial sea water in which sulphate of lime as well as chloride 

 of sodium are present, but from which chloride of calcium is 

 excluded, do not form a new exo-skeleton of carbonate of lime. 

 As soon as chloride of calcium is added, although the sulphate be 

 withheld, shell-formation may go on. The authors of the paper 

 niiuutely describe the share which epithelial and other cells play 

 in secreting, or causing the deposit of, chemical salts in shells 

 and in bone. The histological and chemical processes differ con- 

 siderably in bone, in egg-shells, in the shells of Crustacea, and in 

 the "mantle" of mollusca. 



The Use of Leeches in Bacteriology. 



Dr. Paslernatski has found that a very convenient method for 

 collecting and preserving for cultivation the spirillum of relap- 

 sing-fever is to use leeches. If the leeches are kept in a cold 

 place, the spirilla they contain preserve their vitality for a con- 

 siderable period, much longer than they do when kept in capillary 

 or other glass tubes. When exposed for some time to a tempera- 

 ture of from 37° C. to 30° C, the spirilla were found to undergo 

 transformation into other forms. 



Lead- Poisoning. 



Investigations made this year appear to show, as reported by a 

 contenaporary, that the lead-miner does not really suffer in health 

 more than any other worker under ground, as the ore is not in a 

 condition to be absorbed by the body, but that lead-smelters and 

 all engaged in the manufacture of lead, particulariy white lead, 

 run a very great risk of being contaminated sooner or later. It 

 also appears that at Tyne-side, the chief centre of the English 

 lead trade, there is one type of ailment which is rarely seen else- 

 where, attacking those who have been engaged in the work only 

 a few months, or even weeks, — a fatal disease, the principal 

 victims being girls of from seventeen to twenty-three years of 

 age. They rapidly display symptons of this form of toxemia in 

 the way of severe headache, followed by colic and blindness; and 

 unless they speedily leave work for a considerable period of time, 

 and undergo most careful treatment, the fatal result is rapidly 

 ushered in, usually with epileptiform convulsions and coma. It 

 is remarkable, however, that but little trace of lead is found in 

 their bodies after death, perhaps not more than a few grains in 

 the internal organs, after they have been subjected to the most 

 complete and exhaustive examination. 



LETTERS TO THE EDITOR. 

 Osteological Notes. 

 Virgil never wrote a more truthful or more appropriate line 

 than the one in which he says, 



'■ Felix qui potuit renrm cognoscere causas." 

 How is the fact to be explained, that, with the exception of a 

 single family, the marsupials have no patella, or, at the best, a 



very rudimentary one, when all the other orders of the Mammalia, 

 as well as certain of the reptiles and birds before them, are thus 

 supplied ? 



The patella is the largest of the sesamoid bones, and, like the 

 other sesamoids, is developed in the course of a muscle or tendon, 

 wherever marked friction occurs, or where protection or increased 

 leverage is demanded. Placed on the anterior surface of thb 

 knee joint in the conjoined tendon of the four extensors of the leg 

 {quadriceps extensor), this bone is of a triangular form, its base 

 being turned upwards to receive the above tendon, and its apex 

 downwards to be united by the strong ligament to the tubercle 

 of the tibia. 



John Bell says, " The patella is manifestly useful chiefly as a 

 lever, gliding upon the fore-part of the thigh-bone, upon the 

 smooth surface which is betwixt the condyles. The projection of 

 this bone upon the knee removes the acting force from the centre 

 of motion so as to increase the power; and it is beautifully con- 

 trived, that while the knee is bent, and the muscles at rest, as in 

 sitting, the patella sinks down concealed into a hollow of the 

 knee. When the muscleo.begin to act, the patella begins to rise 

 from this hollow; in proporiion as they contract, they lose their 

 strength, but the patella, gradually rising, increases the power, 

 and, when the contraction is near'y perfect, the patella has risen 

 to the summit of the knee; so that tiie rising of the patella raises 

 the mechanical power of the joint in e^act proportion as the con- 

 traction expands the living contractible power of the muscles." 



In the marsupials the patella may be entirely absent, or its 

 place may be supplied by a cartilaginous disk, with occasionally 

 slight specks of bony matter intermingled, or, in some cases, by a 

 simple broadened expansion of the tendon. In only one family, 

 the bandicoots (PeramelidcB), is this bone fully developed, and the 

 groove in the femur, for its action, well marked. In the phalan- 

 gers (Phalangistidce), as also in the native cats (Dasyuridoe), the 

 groove is broad and shallow, and the patella but slightly devel- 

 oped, consisting of a moderate thickening of the tendon quadri- 

 ceps extensor. 



In the flying phalangers (Petaurists) , in the native bear {Phas- 

 colarcios cenoreus), and in the wombat {Phascolomys), as well as 

 in the banded ant-eater {Myrmecobius) , the anterior distal surface 

 of the femur is almost plane from side to side, exhibiting no de- 

 pression for a p&tella, which does not exist. In the opossums 

 {Didelphidce) there is a slight thickening of the tendon. In the 

 typical kangaroo (Macropus), as well as in the kangaroo rat 

 (Hypsiprymnus), the muscular tendon is fairly developed, and 

 the femoral groove correspondingly well marked. Owen says 

 that he has found a small patella in Macropus bennetti. 



In searching for a solution of the problem thus presented, the 

 low organization of the order of the Marsupialia must be espe- 

 cially recognized. They have close affinities with the reptiles and 

 birds (Sauropsida), in most of which no patella exists. The pres- 

 ence of this bone in certain lizards among the reptiles, and in cer- 

 tain birds, offers no greater anomaly than its existence solely in 

 one family of the marsupials. Then, again, we find similar pro- 

 visions made for its absence in the reptiles, birds, and marsu- 

 pials; viz., a prolongation and modification of that tubercle of the 

 tibia which thus supplies increased leverage. 



Moreover, there is nothing observable in the anatomy or in the 

 habits of the bandicoots that would lead us to suppose that they 

 specially needed a normally constructed patella. They are small, 

 rat-like animals, about eighteen inches in length, having a singular 

 gait, which is made up of jumping and running; and they live 

 among stony ridges in the eastern and south-eastern portions of 

 Australia. They are allied in their food to the placental Insec- 

 tivora. 



Cope, in his "Hard Parts of the Mammalia," says, " The ex- 

 istence of tibia and fibula of subequal size gave rise to two distal 

 articular surfaces of the femui-. The constant use of these in 

 flexion and extension gave them the convexity which they possess 

 in the Mammalia, — a process already commenced in the Reptilia. 

 The strong tendon of the rectus muscles passing over the anterior 

 face of the extremity gave rise to the rotular groove. This became 

 better defined and more important after the development in 

 placental mammals of a sesamoid bone or patella in the tendon." 



