1888.] Protection against Infectious Diseases. 151 



which before were large and well formed, degenerate into small and 

 comparatively inconspicuous bodies, the starch apparently being used 

 up in the formation of spores. In all probability there is at this 

 period a formation of xanthophyll, which would account for the 

 yellow colour of the apophysis in the mature condition of the 

 sporangium, and hence the name of the species. 



That the apophysis performs the functions of a leaf, and is there- 

 fore analogous with the leaves of vascular plants, I think there can 

 now be no doubt. And as this structure is a development of the 

 sporophyte, the possibility of its being also homologous either directly 

 or indirectly suggests itself. I am myself inclined to believe that 

 the two are homologous ; but to give a full discussion of that question 

 would be beyond the scope of the present communication. 



IV. " A Contribution to the Knowledge of Protection against 

 Infectious Diseases." By ALFRED LINGAUD, M.B., M.S. Durh., 

 Diplomate in Public Health, Cambridge. Communicated by 

 Dr. E. KLEIN, F.R.S. Received December 3, 1888. 



It has long been known, and it is now a well-established fact, that 

 various eruptive fevers and blood diseases from which the mother may 

 suffer, can be communicated to the foetus in utero. There is evidence 

 also to prove that a disease may be transmitted to the foetus through 

 a mother who is herself insusceptible to contagium, as in the case of a 

 child having been born covered with small-pox eruption, the mother 

 being quite free from it. The following are the diseases upon which 

 the most important observations have been made : Syphilis, small- 

 pox, tuberculosis, anthrax, and relapsing fever. In the three latter 

 the organisms producing these diseases have been found in the body 

 of the foetus at birth, having passed through the placental vessels. 



In the present paper I wish to contribute to the other side of the 

 question, viz., the relation existing between the foetus and its mother, 

 or, in other words, the influence, if any, exerted by the foetus on the 

 mother, when the foetus becomes the subject of an infectious disease con- 

 tracted independently of the mother. All the comments made from 

 this standpoint have, with the exception of one, been in relation to 

 syphilis ; the one being an instance communicated by Vidal, of a 

 lather attacked at the time of conception with small-pox, the foetus at 

 six months being covered, during the whole of which period the mother 

 remained healthy. With regard to syphilis, we are indebted to Colles 

 for the first practical observation noted in 1837, when he cited as a 

 carious fact, that he had never witnessed or even heard of an instance 

 in which a child deriving the infection of syphilis from its parents, 

 h.'id caused an ulceration in the breast of the mother. 



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