158 ORGANISED FLUIDS. 



" Treated by dilute acetic acid, the globules of milk un- 

 dergo, little by little, a remarkable change, some of them 

 become oval or take the form of a biscuit; upon others, 

 appear gradually on one or many points a smaller globule, 

 which rests upon the margin and increases in an insensible 

 manner." * * * " If more acetic acid be added, the milk 

 globules appear, as it were, melted down with smooth but 

 irregular borders : they approach the one to the other, and 

 unite into large masses, which resemble perfectly melted fat 

 which has run along in an irregular manner. When to a 

 drop of milk are added two drops of concentrated acetic acid, 

 and the mixture then placed under the microscope, we no 

 longer perceive any regular globule of milk, or, at least, we 

 discover but very few the most are reduced into one or 

 several irregular particles, which, with the naked eye, may 

 be distinguished upon the surface of the drop which other- 

 wise has become clear. The same changes are produced in 

 the space of a few days, when the milk, abandoned to itself, 

 becomes acid by the metamorphosis of its sugar." * 



These ingenious observations of Henle, like those of 

 Mandl, are yet insufficient to demonstrate the existence of a 

 distinct and organised membrane surrounding the milk glo- 

 bule, although they would be assuredly so, if correct, to 

 render it quite certain that it is enveloped with a coating of 

 a material very distinct from fat, and probably of the nature 

 suggested by Mandl and Henle. 



Here, again, however, it becomes a question whether the 

 appearances noticed by Henle have not been misinterpreted, 

 and whether the internal buttery substance does really pro- 

 trude through apertures in the envelope of the globule occa- 

 sioned by the action of acetic acid : in the first place, it 

 seems to me that the milk globules are too small to allow of 

 the determination of the point in question with any degree 

 of certainty ; and, secondly, that in those instances in which 

 observers might fancy that an escape of the included sub- 

 stance of the globule through its envelope had really oc- 



* Henle, Anat, Gen. p. 521, 522. 



