WILBUR ON CLIMATE AND MORTALITY IN MICHIGAN. 139 



points, nor is tlie cavity entirely closed by the entoderm. That is, on 

 account of the shifting of the cavities toward the exterior, the outer 

 walls of the vesicle have been pushed back so that now the cavity is 

 closed on the outside by the ectoderm alone. Third: This ectoderm 

 closing the vesicles breaks away and the vesicles are thus converted into 

 the open cups of the functional organ. The walls of the cups consist 

 of a single layer of exceedingly high, columnar, goblet cells, which 

 secrete the mucus that renders the organ adhesive. The two layers 

 of ectoderm come close up to the rims of the cavities and thus make 

 it appear that they are continuous with the walls of the cups. But aside 

 from the historical evidences just stated, the fact of the presence of the 

 yolk material which is found at all times in the cells which constitute 

 the organ, up to and including the hatching stage, nuirks these cells as 

 entodermal. 



As was stated, the adhesive organ remains functionally active dur- 

 ing the early life of the larva and enables the animal to attach itself 

 to foreign bodies. As the larva grows stronger and more capable of 

 vigorous muscular activities, the adhesive organ gradually atrophies. As 

 it disappears its cells become vacuolated and leucocytes make their 

 appearance among them. At the same time it is gradually' covered in 

 and pushed beneath the surface by the overlying ectoblast which becomes 

 much thickened. By the time the larva is 20 mm. long no external sign 

 of the organ remains. Sections, iiowever, show that it exists below the 

 surface for a few days, at the end of which it entirely disappears. It 

 is interesting to note that in its atrophy it passes through stages which 

 resemble the degenerating notochord, another entodermal organ. 



The adhesive organ of Amia is therefore entoblastic and is unique 

 as an instance of a vertebrate organ of entoblastic origin which becomes 

 incor])orated in the ectoblast. 



COMPARATIVE STATISTICS OF CLIMATE AND MORTALITY IN 



MICHIGAN. 



BY CRESSY L. WILBUR, M. D., LANSING. 



In this brief note I wish to call attention to only a single point, viz., that 

 an opportunity is now presented for making valuable comparisons be- 

 tween the records of meteorology for this State and the statistics of 

 causes of deaths. 



This has not been possible until very recently. Our present excellent 

 system of registering deaths went into effect on August 29, 1897, and 

 there was published with the December, 1S9S, BuUciUi of Vital Statistics 

 a graphic representation of the relations of the death rates of this State, 

 by months, to the chief elements of sanitary meteorology, temperature 

 and precipitation. Besides the curves representing the total death-rates, 

 lines for two of the most important dangerous communicable diseases, 

 consumption and typhoid fever, are also given. The mortality is further 

 analyzed as urban and rural, thus enabling the study to embrace the 

 well known effects of density of population, and according to its distribu- 

 tion in the four geographical sections of the State. The latter are the 



