518 
the wards, it has been impossible to secure a single one of the insects 
for examination. 
A very striking instance of freedom from attack while on board ship 
(where mosquitoes are generally rare), and infection when detailed for 
shore duty for only five days at Cavite, is given by Medical Director 
Persons, United States Navy, in the case of a squad of marines from 
the U. 8. S. Baltimore. Twenty out of twenty-four marines, who had 
been ashore, contracted the disease after returning to the ship, while 
there was a total absence of infection among those who had remained 
aboard.® 
As to the possibility of a micrococcus being the cause of dengue, as 
claimed by two investigators in 1885 and 1897, I am unable to give 
any evidence. However, this matter was investigated and reported upon 
negatively by the Government Laboratories of the Philippine Islands in 
1902.° Of one thing I am convinced and that is that the disease is not 
infectious in the same sense as is influenza. 
The claims of Eberle’ that he found a “dengue plasmeebic organism” 
which was more minute and more active than the malarial parasite, I 
do not consider well founded. He states that the motion of the 
parasite is so swift, it appearing and disappearing so rapidly that, when 
shown to a microscopist, it is not apt to be seen. He describes and 
pictures in his diagrams sporulating bodies. The fact that he claims 
most satisfactory results in staining these bodies with weak eosin and 
methylene blue would indicate that in stained preparations their dis- 
covery should be one of little difficulty. The statement that he found 
phagocytes literally swarming with the minute organism of dengue 
(which was one-fifth the size of a red cell), and furthermore, an examina- 
tion of this appearance in his diagrams, leads me to question whether he 
might not have been observing an aggregation of blood platelets. In 
many of my films stained by Wright’s method I have seen masses of 
blood platelets which presented an appearance very similar to that 
pictured in Eberle’s diagram. In conclusion I should consider the most 
characteristic blood findings of dengue to be the following: 
1. Absence of a demonstrable protozodn. 
2. Leucopenia. 
3. Diminution of polymorphonuclears. 
4. A striking variation in the percentage of other leucocytes at varying 
periods of the disease. At first a large increase in the small lymphocytes 
is observed, then the appearance of a greater proportion of large lym- 
phocytes, and in the final stages (at the time of the terminal rash and 
during convalescence) a most striking increase in the mononuclears. 
5 Persons, R. C.: Journ. Assoc, Military Surgeons (1905), 17, 324. 
*Report of the Director of the Biological Laboratory from the Annual Report 
of the Superintendent of Government Laboratories (1902), 575. 
™ Eberle, H. A.: N. Y. Med. Journ. (1904), 80, 1207. 
